/* ** 2001 September 15 ** ** The author disclaims copyright to this source code. In place of ** a legal notice, here is a blessing: ** ** May you do good and not evil. ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* ** This module contains C code that generates VDBE code used to process ** the WHERE clause of SQL statements. This module is responsible for ** generating the code that loops through a table looking for applicable ** rows. Indices are selected and used to speed the search when doing ** so is applicable. Because this module is responsible for selecting ** indices, you might also think of this module as the "query optimizer". */ #include "sqliteInt.h" /* ** Trace output macros */ #if defined(SQLITE_TEST) || defined(SQLITE_DEBUG) int sqlite3WhereTrace = 0; #endif #if defined(SQLITE_TEST) && defined(SQLITE_DEBUG) # define WHERETRACE(X) if(sqlite3WhereTrace) sqlite3DebugPrintf X #else # define WHERETRACE(X) #endif /* Forward reference */ typedef struct WhereClause WhereClause; typedef struct WhereMaskSet WhereMaskSet; typedef struct WhereOrInfo WhereOrInfo; typedef struct WhereAndInfo WhereAndInfo; typedef struct WhereCost WhereCost; /* ** The query generator uses an array of instances of this structure to ** help it analyze the subexpressions of the WHERE clause. Each WHERE ** clause subexpression is separated from the others by AND operators, ** usually, or sometimes subexpressions separated by OR. ** ** All WhereTerms are collected into a single WhereClause structure. ** The following identity holds: ** ** WhereTerm.pWC->a[WhereTerm.idx] == WhereTerm ** ** When a term is of the form: ** ** X <op> <expr> ** ** where X is a column name and <op> is one of certain operators, ** then WhereTerm.leftCursor and WhereTerm.u.leftColumn record the ** cursor number and column number for X. WhereTerm.eOperator records ** the <op> using a bitmask encoding defined by WO_xxx below. The ** use of a bitmask encoding for the operator allows us to search ** quickly for terms that match any of several different operators. ** ** A WhereTerm might also be two or more subterms connected by OR: ** ** (t1.X <op> <expr>) OR (t1.Y <op> <expr>) OR .... ** ** In this second case, wtFlag as the TERM_ORINFO set and eOperator==WO_OR ** and the WhereTerm.u.pOrInfo field points to auxiliary information that ** is collected about the ** ** If a term in the WHERE clause does not match either of the two previous ** categories, then eOperator==0. The WhereTerm.pExpr field is still set ** to the original subexpression content and wtFlags is set up appropriately ** but no other fields in the WhereTerm object are meaningful. ** ** When eOperator!=0, prereqRight and prereqAll record sets of cursor numbers, ** but they do so indirectly. A single WhereMaskSet structure translates ** cursor number into bits and the translated bit is stored in the prereq ** fields. The translation is used in order to maximize the number of ** bits that will fit in a Bitmask. The VDBE cursor numbers might be ** spread out over the non-negative integers. For example, the cursor ** numbers might be 3, 8, 9, 10, 20, 23, 41, and 45. The WhereMaskSet ** translates these sparse cursor numbers into consecutive integers ** beginning with 0 in order to make the best possible use of the available ** bits in the Bitmask. So, in the example above, the cursor numbers ** would be mapped into integers 0 through 7. ** ** The number of terms in a join is limited by the number of bits ** in prereqRight and prereqAll. The default is 64 bits, hence SQLite ** is only able to process joins with 64 or fewer tables. */ typedef struct WhereTerm WhereTerm; struct WhereTerm { Expr *pExpr; /* Pointer to the subexpression that is this term */ int iParent; /* Disable pWC->a[iParent] when this term disabled */ int leftCursor; /* Cursor number of X in "X <op> <expr>" */ union { int leftColumn; /* Column number of X in "X <op> <expr>" */ WhereOrInfo *pOrInfo; /* Extra information if eOperator==WO_OR */ WhereAndInfo *pAndInfo; /* Extra information if eOperator==WO_AND */ } u; u16 eOperator; /* A WO_xx value describing <op> */ u8 wtFlags; /* TERM_xxx bit flags. See below */ u8 nChild; /* Number of children that must disable us */ WhereClause *pWC; /* The clause this term is part of */ Bitmask prereqRight; /* Bitmask of tables used by pExpr->pRight */ Bitmask prereqAll; /* Bitmask of tables referenced by pExpr */ }; /* ** Allowed values of WhereTerm.wtFlags */ #define TERM_DYNAMIC 0x01 /* Need to call sqlite3ExprDelete(db, pExpr) */ #define TERM_VIRTUAL 0x02 /* Added by the optimizer. Do not code */ #define TERM_CODED 0x04 /* This term is already coded */ #define TERM_COPIED 0x08 /* Has a child */ #define TERM_ORINFO 0x10 /* Need to free the WhereTerm.u.pOrInfo object */ #define TERM_ANDINFO 0x20 /* Need to free the WhereTerm.u.pAndInfo obj */ #define TERM_OR_OK 0x40 /* Used during OR-clause processing */ #ifdef SQLITE_ENABLE_STAT2 # define TERM_VNULL 0x80 /* Manufactured x>NULL or x<=NULL term */ #else # define TERM_VNULL 0x00 /* Disabled if not using stat2 */ #endif /* ** An instance of the following structure holds all information about a ** WHERE clause. Mostly this is a container for one or more WhereTerms. */ struct WhereClause { Parse *pParse; /* The parser context */ WhereMaskSet *pMaskSet; /* Mapping of table cursor numbers to bitmasks */ Bitmask vmask; /* Bitmask identifying virtual table cursors */ u8 op; /* Split operator. TK_AND or TK_OR */ int nTerm; /* Number of terms */ int nSlot; /* Number of entries in a[] */ WhereTerm *a; /* Each a[] describes a term of the WHERE cluase */ #if defined(SQLITE_SMALL_STACK) WhereTerm aStatic[1]; /* Initial static space for a[] */ #else WhereTerm aStatic[8]; /* Initial static space for a[] */ #endif }; /* ** A WhereTerm with eOperator==WO_OR has its u.pOrInfo pointer set to ** a dynamically allocated instance of the following structure. */ struct WhereOrInfo { WhereClause wc; /* Decomposition into subterms */ Bitmask indexable; /* Bitmask of all indexable tables in the clause */ }; /* ** A WhereTerm with eOperator==WO_AND has its u.pAndInfo pointer set to ** a dynamically allocated instance of the following structure. */ struct WhereAndInfo { WhereClause wc; /* The subexpression broken out */ }; /* ** An instance of the following structure keeps track of a mapping ** between VDBE cursor numbers and bits of the bitmasks in WhereTerm. ** ** The VDBE cursor numbers are small integers contained in ** SrcList_item.iCursor and Expr.iTable fields. For any given WHERE ** clause, the cursor numbers might not begin with 0 and they might ** contain gaps in the numbering sequence. But we want to make maximum ** use of the bits in our bitmasks. This structure provides a mapping ** from the sparse cursor numbers into consecutive integers beginning ** with 0. ** ** If WhereMaskSet.ix[A]==B it means that The A-th bit of a Bitmask ** corresponds VDBE cursor number B. The A-th bit of a bitmask is 1<<A. ** ** For example, if the WHERE clause expression used these VDBE ** cursors: 4, 5, 8, 29, 57, 73. Then the WhereMaskSet structure ** would map those cursor numbers into bits 0 through 5. ** ** Note that the mapping is not necessarily ordered. In the example ** above, the mapping might go like this: 4->3, 5->1, 8->2, 29->0, ** 57->5, 73->4. Or one of 719 other combinations might be used. It ** does not really matter. What is important is that sparse cursor ** numbers all get mapped into bit numbers that begin with 0 and contain ** no gaps. */ struct WhereMaskSet { int n; /* Number of assigned cursor values */ int ix[BMS]; /* Cursor assigned to each bit */ }; /* ** A WhereCost object records a lookup strategy and the estimated ** cost of pursuing that strategy. */ struct WhereCost { WherePlan plan; /* The lookup strategy */ double rCost; /* Overall cost of pursuing this search strategy */ Bitmask used; /* Bitmask of cursors used by this plan */ }; /* ** Bitmasks for the operators that indices are able to exploit. An ** OR-ed combination of these values can be used when searching for ** terms in the where clause. */ #define WO_IN 0x001 #define WO_EQ 0x002 #define WO_LT (WO_EQ<<(TK_LT-TK_EQ)) #define WO_LE (WO_EQ<<(TK_LE-TK_EQ)) #define WO_GT (WO_EQ<<(TK_GT-TK_EQ)) #define WO_GE (WO_EQ<<(TK_GE-TK_EQ)) #define WO_MATCH 0x040 #define WO_ISNULL 0x080 #define WO_OR 0x100 /* Two or more OR-connected terms */ #define WO_AND 0x200 /* Two or more AND-connected terms */ #define WO_NOOP 0x800 /* This term does not restrict search space */ #define WO_ALL 0xfff /* Mask of all possible WO_* values */ #define WO_SINGLE 0x0ff /* Mask of all non-compound WO_* values */ /* ** Value for wsFlags returned by bestIndex() and stored in ** WhereLevel.wsFlags. These flags determine which search ** strategies are appropriate. ** ** The least significant 12 bits is reserved as a mask for WO_ values above. ** The WhereLevel.wsFlags field is usually set to WO_IN|WO_EQ|WO_ISNULL. ** But if the table is the right table of a left join, WhereLevel.wsFlags ** is set to WO_IN|WO_EQ. The WhereLevel.wsFlags field can then be used as ** the "op" parameter to findTerm when we are resolving equality constraints. ** ISNULL constraints will then not be used on the right table of a left ** join. Tickets #2177 and #2189. */ #define WHERE_ROWID_EQ 0x00001000 /* rowid=EXPR or rowid IN (...) */ #define WHERE_ROWID_RANGE 0x00002000 /* rowid<EXPR and/or rowid>EXPR */ #define WHERE_COLUMN_EQ 0x00010000 /* x=EXPR or x IN (...) or x IS NULL */ #define WHERE_COLUMN_RANGE 0x00020000 /* x<EXPR and/or x>EXPR */ #define WHERE_COLUMN_IN 0x00040000 /* x IN (...) */ #define WHERE_COLUMN_NULL 0x00080000 /* x IS NULL */ #define WHERE_INDEXED 0x000f0000 /* Anything that uses an index */ #define WHERE_NOT_FULLSCAN 0x100f3000 /* Does not do a full table scan */ #define WHERE_IN_ABLE 0x000f1000 /* Able to support an IN operator */ #define WHERE_TOP_LIMIT 0x00100000 /* x<EXPR or x<=EXPR constraint */ #define WHERE_BTM_LIMIT 0x00200000 /* x>EXPR or x>=EXPR constraint */ #define WHERE_BOTH_LIMIT 0x00300000 /* Both x>EXPR and x<EXPR */ #define WHERE_IDX_ONLY 0x00800000 /* Use index only - omit table */ #define WHERE_ORDERBY 0x01000000 /* Output will appear in correct order */ #define WHERE_REVERSE 0x02000000 /* Scan in reverse order */ #define WHERE_UNIQUE 0x04000000 /* Selects no more than one row */ #define WHERE_VIRTUALTABLE 0x08000000 /* Use virtual-table processing */ #define WHERE_MULTI_OR 0x10000000 /* OR using multiple indices */ #define WHERE_TEMP_INDEX 0x20000000 /* Uses an ephemeral index */ /* ** Initialize a preallocated WhereClause structure. */ static void whereClauseInit( WhereClause *pWC, /* The WhereClause to be initialized */ Parse *pParse, /* The parsing context */ WhereMaskSet *pMaskSet /* Mapping from table cursor numbers to bitmasks */ ){ pWC->pParse = pParse; pWC->pMaskSet = pMaskSet; pWC->nTerm = 0; pWC->nSlot = ArraySize(pWC->aStatic); pWC->a = pWC->aStatic; pWC->vmask = 0; } /* Forward reference */ static void whereClauseClear(WhereClause*); /* ** Deallocate all memory associated with a WhereOrInfo object. */ static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){ whereClauseClear(&p->wc); sqlite3DbFree(db, p); } /* ** Deallocate all memory associated with a WhereAndInfo object. */ static void whereAndInfoDelete(sqlite3 *db, WhereAndInfo *p){ whereClauseClear(&p->wc); sqlite3DbFree(db, p); } /* ** Deallocate a WhereClause structure. The WhereClause structure ** itself is not freed. This routine is the inverse of whereClauseInit(). */ static void whereClauseClear(WhereClause *pWC){ int i; WhereTerm *a; sqlite3 *db = pWC->pParse->db; for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){ if( a->wtFlags & TERM_DYNAMIC ){ sqlite3ExprDelete(db, a->pExpr); } if( a->wtFlags & TERM_ORINFO ){ whereOrInfoDelete(db, a->u.pOrInfo); }else if( a->wtFlags & TERM_ANDINFO ){ whereAndInfoDelete(db, a->u.pAndInfo); } } if( pWC->a!=pWC->aStatic ){ sqlite3DbFree(db, pWC->a); } } /* ** Add a single new WhereTerm entry to the WhereClause object pWC. ** The new WhereTerm object is constructed from Expr p and with wtFlags. ** The index in pWC->a[] of the new WhereTerm is returned on success. ** 0 is returned if the new WhereTerm could not be added due to a memory ** allocation error. The memory allocation failure will be recorded in ** the db->mallocFailed flag so that higher-level functions can detect it. ** ** This routine will increase the size of the pWC->a[] array as necessary. ** ** If the wtFlags argument includes TERM_DYNAMIC, then responsibility ** for freeing the expression p is assumed by the WhereClause object pWC. ** This is true even if this routine fails to allocate a new WhereTerm. ** ** WARNING: This routine might reallocate the space used to store ** WhereTerms. All pointers to WhereTerms should be invalidated after ** calling this routine. Such pointers may be reinitialized by referencing ** the pWC->a[] array. */ static int whereClauseInsert(WhereClause *pWC, Expr *p, u8 wtFlags){ WhereTerm *pTerm; int idx; testcase( wtFlags & TERM_VIRTUAL ); /* EV: R-00211-15100 */ if( pWC->nTerm>=pWC->nSlot ){ WhereTerm *pOld = pWC->a; sqlite3 *db = pWC->pParse->db; pWC->a = sqlite3DbMallocRaw(db, sizeof(pWC->a[0])*pWC->nSlot*2 ); if( pWC->a==0 ){ if( wtFlags & TERM_DYNAMIC ){ sqlite3ExprDelete(db, p); } pWC->a = pOld; return 0; } memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm); if( pOld!=pWC->aStatic ){ sqlite3DbFree(db, pOld); } pWC->nSlot = sqlite3DbMallocSize(db, pWC->a)/sizeof(pWC->a[0]); } pTerm = &pWC->a[idx = pWC->nTerm++]; pTerm->pExpr = p; pTerm->wtFlags = wtFlags; pTerm->pWC = pWC; pTerm->iParent = -1; return idx; } /* ** This routine identifies subexpressions in the WHERE clause where ** each subexpression is separated by the AND operator or some other ** operator specified in the op parameter. The WhereClause structure ** is filled with pointers to subexpressions. For example: ** ** WHERE a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22) ** \________/ \_______________/ \________________/ ** slot[0] slot[1] slot[2] ** ** The original WHERE clause in pExpr is unaltered. All this routine ** does is make slot[] entries point to substructure within pExpr. ** ** In the previous sentence and in the diagram, "slot[]" refers to ** the WhereClause.a[] array. The slot[] array grows as needed to contain ** all terms of the WHERE clause. */ static void whereSplit(WhereClause *pWC, Expr *pExpr, int op){ pWC->op = (u8)op; if( pExpr==0 ) return; if( pExpr->op!=op ){ whereClauseInsert(pWC, pExpr, 0); }else{ whereSplit(pWC, pExpr->pLeft, op); whereSplit(pWC, pExpr->pRight, op); } } /* ** Initialize an expression mask set (a WhereMaskSet object) */ #define initMaskSet(P) memset(P, 0, sizeof(*P)) /* ** Return the bitmask for the given cursor number. Return 0 if ** iCursor is not in the set. */ static Bitmask getMask(WhereMaskSet *pMaskSet, int iCursor){ int i; assert( pMaskSet->n<=(int)sizeof(Bitmask)*8 ); for(i=0; i<pMaskSet->n; i++){ if( pMaskSet->ix[i]==iCursor ){ return ((Bitmask)1)<<i; } } return 0; } /* ** Create a new mask for cursor iCursor. ** ** There is one cursor per table in the FROM clause. The number of ** tables in the FROM clause is limited by a test early in the ** sqlite3WhereBegin() routine. So we know that the pMaskSet->ix[] ** array will never overflow. */ static void createMask(WhereMaskSet *pMaskSet, int iCursor){ assert( pMaskSet->n < ArraySize(pMaskSet->ix) ); pMaskSet->ix[pMaskSet->n++] = iCursor; } /* ** This routine walks (recursively) an expression tree and generates ** a bitmask indicating which tables are used in that expression ** tree. ** ** In order for this routine to work, the calling function must have ** previously invoked sqlite3ResolveExprNames() on the expression. See ** the header comment on that routine for additional information. ** The sqlite3ResolveExprNames() routines looks for column names and ** sets their opcodes to TK_COLUMN and their Expr.iTable fields to ** the VDBE cursor number of the table. This routine just has to ** translate the cursor numbers into bitmask values and OR all ** the bitmasks together. */ static Bitmask exprListTableUsage(WhereMaskSet*, ExprList*); static Bitmask exprSelectTableUsage(WhereMaskSet*, Select*); static Bitmask exprTableUsage(WhereMaskSet *pMaskSet, Expr *p){ Bitmask mask = 0; if( p==0 ) return 0; if( p->op==TK_COLUMN ){ mask = getMask(pMaskSet, p->iTable); return mask; } mask = exprTableUsage(pMaskSet, p->pRight); mask |= exprTableUsage(pMaskSet, p->pLeft); if( ExprHasProperty(p, EP_xIsSelect) ){ mask |= exprSelectTableUsage(pMaskSet, p->x.pSelect); }else{ mask |= exprListTableUsage(pMaskSet, p->x.pList); } return mask; } static Bitmask exprListTableUsage(WhereMaskSet *pMaskSet, ExprList *pList){ int i; Bitmask mask = 0; if( pList ){ for(i=0; i<pList->nExpr; i++){ mask |= exprTableUsage(pMaskSet, pList->a[i].pExpr); } } return mask; } static Bitmask exprSelectTableUsage(WhereMaskSet *pMaskSet, Select *pS){ Bitmask mask = 0; while( pS ){ mask |= exprListTableUsage(pMaskSet, pS->pEList); mask |= exprListTableUsage(pMaskSet, pS->pGroupBy); mask |= exprListTableUsage(pMaskSet, pS->pOrderBy); mask |= exprTableUsage(pMaskSet, pS->pWhere); mask |= exprTableUsage(pMaskSet, pS->pHaving); pS = pS->pPrior; } return mask; } /* ** Return TRUE if the given operator is one of the operators that is ** allowed for an indexable WHERE clause term. The allowed operators are ** "=", "<", ">", "<=", ">=", and "IN". ** ** IMPLEMENTATION-OF: R-59926-26393 To be usable by an index a term must be ** of one of the following forms: column = expression column > expression ** column >= expression column < expression column <= expression ** expression = column expression > column expression >= column ** expression < column expression <= column column IN ** (expression-list) column IN (subquery) column IS NULL */ static int allowedOp(int op){ assert( TK_GT>TK_EQ && TK_GT<TK_GE ); assert( TK_LT>TK_EQ && TK_LT<TK_GE ); assert( TK_LE>TK_EQ && TK_LE<TK_GE ); assert( TK_GE==TK_EQ+4 ); return op==TK_IN || (op>=TK_EQ && op<=TK_GE) || op==TK_ISNULL; } /* ** Swap two objects of type TYPE. */ #define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;} /* ** Commute a comparison operator. Expressions of the form "X op Y" ** are converted into "Y op X". ** ** If a collation sequence is associated with either the left or right ** side of the comparison, it remains associated with the same side after ** the commutation. So "Y collate NOCASE op X" becomes ** "X collate NOCASE op Y". This is because any collation sequence on ** the left hand side of a comparison overrides any collation sequence ** attached to the right. For the same reason the EP_ExpCollate flag ** is not commuted. */ static void exprCommute(Parse *pParse, Expr *pExpr){ u16 expRight = (pExpr->pRight->flags & EP_ExpCollate); u16 expLeft = (pExpr->pLeft->flags & EP_ExpCollate); assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN ); pExpr->pRight->pColl = sqlite3ExprCollSeq(pParse, pExpr->pRight); pExpr->pLeft->pColl = sqlite3ExprCollSeq(pParse, pExpr->pLeft); SWAP(CollSeq*,pExpr->pRight->pColl,pExpr->pLeft->pColl); pExpr->pRight->flags = (pExpr->pRight->flags & ~EP_ExpCollate) | expLeft; pExpr->pLeft->flags = (pExpr->pLeft->flags & ~EP_ExpCollate) | expRight; SWAP(Expr*,pExpr->pRight,pExpr->pLeft); if( pExpr->op>=TK_GT ){ assert( TK_LT==TK_GT+2 ); assert( TK_GE==TK_LE+2 ); assert( TK_GT>TK_EQ ); assert( TK_GT<TK_LE ); assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE ); pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT; } } /* ** Translate from TK_xx operator to WO_xx bitmask. */ static u16 operatorMask(int op){ u16 c; assert( allowedOp(op) ); if( op==TK_IN ){ c = WO_IN; }else if( op==TK_ISNULL ){ c = WO_ISNULL; }else{ assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff ); c = (u16)(WO_EQ<<(op-TK_EQ)); } assert( op!=TK_ISNULL || c==WO_ISNULL ); assert( op!=TK_IN || c==WO_IN ); assert( op!=TK_EQ || c==WO_EQ ); assert( op!=TK_LT || c==WO_LT ); assert( op!=TK_LE || c==WO_LE ); assert( op!=TK_GT || c==WO_GT ); assert( op!=TK_GE || c==WO_GE ); return c; } /* ** Search for a term in the WHERE clause that is of the form "X <op> <expr>" ** where X is a reference to the iColumn of table iCur and <op> is one of ** the WO_xx operator codes specified by the op parameter. ** Return a pointer to the term. Return 0 if not found. */ static WhereTerm *findTerm( WhereClause *pWC, /* The WHERE clause to be searched */ int iCur, /* Cursor number of LHS */ int iColumn, /* Column number of LHS */ Bitmask notReady, /* RHS must not overlap with this mask */ u32 op, /* Mask of WO_xx values describing operator */ Index *pIdx /* Must be compatible with this index, if not NULL */ ){ WhereTerm *pTerm; int k; assert( iCur>=0 ); op &= WO_ALL; for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){ if( pTerm->leftCursor==iCur && (pTerm->prereqRight & notReady)==0 && pTerm->u.leftColumn==iColumn && (pTerm->eOperator & op)!=0 ){ if( pIdx && pTerm->eOperator!=WO_ISNULL ){ Expr *pX = pTerm->pExpr; CollSeq *pColl; char idxaff; int j; Parse *pParse = pWC->pParse; idxaff = pIdx->pTable->aCol[iColumn].affinity; if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue; /* Figure out the collation sequence required from an index for ** it to be useful for optimising expression pX. Store this ** value in variable pColl. */ assert(pX->pLeft); pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight); assert(pColl || pParse->nErr); for(j=0; pIdx->aiColumn[j]!=iColumn; j++){ if( NEVER(j>=pIdx->nColumn) ) return 0; } if( pColl && sqlite3StrICmp(pColl->zName, pIdx->azColl[j]) ) continue; } return pTerm; } } return 0; } /* Forward reference */ static void exprAnalyze(SrcList*, WhereClause*, int); /* ** Call exprAnalyze on all terms in a WHERE clause. ** ** */ static void exprAnalyzeAll( SrcList *pTabList, /* the FROM clause */ WhereClause *pWC /* the WHERE clause to be analyzed */ ){ int i; for(i=pWC->nTerm-1; i>=0; i--){ exprAnalyze(pTabList, pWC, i); } } #ifndef SQLITE_OMIT_LIKE_OPTIMIZATION /* ** Check to see if the given expression is a LIKE or GLOB operator that ** can be optimized using inequality constraints. Return TRUE if it is ** so and false if not. ** ** In order for the operator to be optimizible, the RHS must be a string ** literal that does not begin with a wildcard. */ static int isLikeOrGlob( Parse *pParse, /* Parsing and code generating context */ Expr *pExpr, /* Test this expression */ Expr **ppPrefix, /* Pointer to TK_STRING expression with pattern prefix */ int *pisComplete, /* True if the only wildcard is % in the last character */ int *pnoCase /* True if uppercase is equivalent to lowercase */ ){ const char *z = 0; /* String on RHS of LIKE operator */ Expr *pRight, *pLeft; /* Right and left size of LIKE operator */ ExprList *pList; /* List of operands to the LIKE operator */ int c; /* One character in z[] */ int cnt; /* Number of non-wildcard prefix characters */ char wc[3]; /* Wildcard characters */ sqlite3 *db = pParse->db; /* Database connection */ sqlite3_value *pVal = 0; int op; /* Opcode of pRight */ if( !sqlite3IsLikeFunction(db, pExpr, pnoCase, wc) ){ return 0; } #ifdef SQLITE_EBCDIC if( *pnoCase ) return 0; #endif pList = pExpr->x.pList; pLeft = pList->a[1].pExpr; if( pLeft->op!=TK_COLUMN || sqlite3ExprAffinity(pLeft)!=SQLITE_AFF_TEXT ){ /* IMP: R-02065-49465 The left-hand side of the LIKE or GLOB operator must ** be the name of an indexed column with TEXT affinity. */ return 0; } assert( pLeft->iColumn!=(-1) ); /* Because IPK never has AFF_TEXT */ pRight = pList->a[0].pExpr; op = pRight->op; if( op==TK_REGISTER ){ op = pRight->op2; } if( op==TK_VARIABLE ){ Vdbe *pReprepare = pParse->pReprepare; int iCol = pRight->iColumn; pVal = sqlite3VdbeGetValue(pReprepare, iCol, SQLITE_AFF_NONE); if( pVal && sqlite3_value_type(pVal)==SQLITE_TEXT ){ z = (char *)sqlite3_value_text(pVal); } sqlite3VdbeSetVarmask(pParse->pVdbe, iCol); /* IMP: R-23257-02778 */ assert( pRight->op==TK_VARIABLE || pRight->op==TK_REGISTER ); }else if( op==TK_STRING ){ z = pRight->u.zToken; } if( z ){ cnt = 0; while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){ cnt++; } if( cnt!=0 && 255!=(u8)z[cnt-1] ){ Expr *pPrefix; *pisComplete = c==wc[0] && z[cnt+1]==0; pPrefix = sqlite3Expr(db, TK_STRING, z); if( pPrefix ) pPrefix->u.zToken[cnt] = 0; *ppPrefix = pPrefix; if( op==TK_VARIABLE ){ Vdbe *v = pParse->pVdbe; sqlite3VdbeSetVarmask(v, pRight->iColumn); /* IMP: R-23257-02778 */ if( *pisComplete && pRight->u.zToken[1] ){ /* If the rhs of the LIKE expression is a variable, and the current ** value of the variable means there is no need to invoke the LIKE ** function, then no OP_Variable will be added to the program. ** This causes problems for the sqlite3_bind_parameter_name() ** API. To workaround them, add a dummy OP_Variable here. */ int r1 = sqlite3GetTempReg(pParse); sqlite3ExprCodeTarget(pParse, pRight, r1); sqlite3VdbeChangeP3(v, sqlite3VdbeCurrentAddr(v)-1, 0); sqlite3ReleaseTempReg(pParse, r1); } } }else{ z = 0; } } sqlite3ValueFree(pVal); return (z!=0); } #endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */ #ifndef SQLITE_OMIT_VIRTUALTABLE /* ** Check to see if the given expression is of the form ** ** column MATCH expr ** ** If it is then return TRUE. If not, return FALSE. */ static int isMatchOfColumn( Expr *pExpr /* Test this expression */ ){ ExprList *pList; if( pExpr->op!=TK_FUNCTION ){ return 0; } if( sqlite3StrICmp(pExpr->u.zToken,"match")!=0 ){ return 0; } pList = pExpr->x.pList; if( pList->nExpr!=2 ){ return 0; } if( pList->a[1].pExpr->op != TK_COLUMN ){ return 0; } return 1; } #endif /* SQLITE_OMIT_VIRTUALTABLE */ /* ** If the pBase expression originated in the ON or USING clause of ** a join, then transfer the appropriate markings over to derived. */ static void transferJoinMarkings(Expr *pDerived, Expr *pBase){ pDerived->flags |= pBase->flags & EP_FromJoin; pDerived->iRightJoinTable = pBase->iRightJoinTable; } #if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY) /* ** Analyze a term that consists of two or more OR-connected ** subterms. So in: ** ** ... WHERE (a=5) AND (b=7 OR c=9 OR d=13) AND (d=13) ** ^^^^^^^^^^^^^^^^^^^^ ** ** This routine analyzes terms such as the middle term in the above example. ** A WhereOrTerm object is computed and attached to the term under ** analysis, regardless of the outcome of the analysis. Hence: ** ** WhereTerm.wtFlags |= TERM_ORINFO ** WhereTerm.u.pOrInfo = a dynamically allocated WhereOrTerm object ** ** The term being analyzed must have two or more of OR-connected subterms. ** A single subterm might be a set of AND-connected sub-subterms. ** Examples of terms under analysis: ** ** (A) t1.x=t2.y OR t1.x=t2.z OR t1.y=15 OR t1.z=t3.a+5 ** (B) x=expr1 OR expr2=x OR x=expr3 ** (C) t1.x=t2.y OR (t1.x=t2.z AND t1.y=15) ** (D) x=expr1 OR (y>11 AND y<22 AND z LIKE '*hello*') ** (E) (p.a=1 AND q.b=2 AND r.c=3) OR (p.x=4 AND q.y=5 AND r.z=6) ** ** CASE 1: ** ** If all subterms are of the form T.C=expr for some single column of C ** a single table T (as shown in example B above) then create a new virtual ** term that is an equivalent IN expression. In other words, if the term ** being analyzed is: ** ** x = expr1 OR expr2 = x OR x = expr3 ** ** then create a new virtual term like this: ** ** x IN (expr1,expr2,expr3) ** ** CASE 2: ** ** If all subterms are indexable by a single table T, then set ** ** WhereTerm.eOperator = WO_OR ** WhereTerm.u.pOrInfo->indexable |= the cursor number for table T ** ** A subterm is "indexable" if it is of the form ** "T.C <op> <expr>" where C is any column of table T and ** <op> is one of "=", "<", "<=", ">", ">=", "IS NULL", or "IN". ** A subterm is also indexable if it is an AND of two or more ** subsubterms at least one of which is indexable. Indexable AND ** subterms have their eOperator set to WO_AND and they have ** u.pAndInfo set to a dynamically allocated WhereAndTerm object. ** ** From another point of view, "indexable" means that the subterm could ** potentially be used with an index if an appropriate index exists. ** This analysis does not consider whether or not the index exists; that ** is something the bestIndex() routine will determine. This analysis ** only looks at whether subterms appropriate for indexing exist. ** ** All examples A through E above all satisfy case 2. But if a term ** also statisfies case 1 (such as B) we know that the optimizer will ** always prefer case 1, so in that case we pretend that case 2 is not ** satisfied. ** ** It might be the case that multiple tables are indexable. For example, ** (E) above is indexable on tables P, Q, and R. ** ** Terms that satisfy case 2 are candidates for lookup by using ** separate indices to find rowids for each subterm and composing ** the union of all rowids using a RowSet object. This is similar ** to "bitmap indices" in other database engines. ** ** OTHERWISE: ** ** If neither case 1 nor case 2 apply, then leave the eOperator set to ** zero. This term is not useful for search. */ static void exprAnalyzeOrTerm( SrcList *pSrc, /* the FROM clause */ WhereClause *pWC, /* the complete WHERE clause */ int idxTerm /* Index of the OR-term to be analyzed */ ){ Parse *pParse = pWC->pParse; /* Parser context */ sqlite3 *db = pParse->db; /* Database connection */ WhereTerm *pTerm = &pWC->a[idxTerm]; /* The term to be analyzed */ Expr *pExpr = pTerm->pExpr; /* The expression of the term */ WhereMaskSet *pMaskSet = pWC->pMaskSet; /* Table use masks */ int i; /* Loop counters */ WhereClause *pOrWc; /* Breakup of pTerm into subterms */ WhereTerm *pOrTerm; /* A Sub-term within the pOrWc */ WhereOrInfo *pOrInfo; /* Additional information associated with pTerm */ Bitmask chngToIN; /* Tables that might satisfy case 1 */ Bitmask indexable; /* Tables that are indexable, satisfying case 2 */ /* ** Break the OR clause into its separate subterms. The subterms are ** stored in a WhereClause structure containing within the WhereOrInfo ** object that is attached to the original OR clause term. */ assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 ); assert( pExpr->op==TK_OR ); pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo)); if( pOrInfo==0 ) return; pTerm->wtFlags |= TERM_ORINFO; pOrWc = &pOrInfo->wc; whereClauseInit(pOrWc, pWC->pParse, pMaskSet); whereSplit(pOrWc, pExpr, TK_OR); exprAnalyzeAll(pSrc, pOrWc); if( db->mallocFailed ) return; assert( pOrWc->nTerm>=2 ); /* ** Compute the set of tables that might satisfy cases 1 or 2. */ indexable = ~(Bitmask)0; chngToIN = ~(pWC->vmask); for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0 && indexable; i--, pOrTerm++){ if( (pOrTerm->eOperator & WO_SINGLE)==0 ){ WhereAndInfo *pAndInfo; assert( pOrTerm->eOperator==0 ); assert( (pOrTerm->wtFlags & (TERM_ANDINFO|TERM_ORINFO))==0 ); chngToIN = 0; pAndInfo = sqlite3DbMallocRaw(db, sizeof(*pAndInfo)); if( pAndInfo ){ WhereClause *pAndWC; WhereTerm *pAndTerm; int j; Bitmask b = 0; pOrTerm->u.pAndInfo = pAndInfo; pOrTerm->wtFlags |= TERM_ANDINFO; pOrTerm->eOperator = WO_AND; pAndWC = &pAndInfo->wc; whereClauseInit(pAndWC, pWC->pParse, pMaskSet); whereSplit(pAndWC, pOrTerm->pExpr, TK_AND); exprAnalyzeAll(pSrc, pAndWC); testcase( db->mallocFailed ); if( !db->mallocFailed ){ for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){ assert( pAndTerm->pExpr ); if( allowedOp(pAndTerm->pExpr->op) ){ b |= getMask(pMaskSet, pAndTerm->leftCursor); } } } indexable &= b; } }else if( pOrTerm->wtFlags & TERM_COPIED ){ /* Skip this term for now. We revisit it when we process the ** corresponding TERM_VIRTUAL term */ }else{ Bitmask b; b = getMask(pMaskSet, pOrTerm->leftCursor); if( pOrTerm->wtFlags & TERM_VIRTUAL ){ WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent]; b |= getMask(pMaskSet, pOther->leftCursor); } indexable &= b; if( pOrTerm->eOperator!=WO_EQ ){ chngToIN = 0; }else{ chngToIN &= b; } } } /* ** Record the set of tables that satisfy case 2. The set might be ** empty. */ pOrInfo->indexable = indexable; pTerm->eOperator = indexable==0 ? 0 : WO_OR; /* ** chngToIN holds a set of tables that *might* satisfy case 1. But ** we have to do some additional checking to see if case 1 really ** is satisfied. ** ** chngToIN will hold either 0, 1, or 2 bits. The 0-bit case means ** that there is no possibility of transforming the OR clause into an ** IN operator because one or more terms in the OR clause contain ** something other than == on a column in the single table. The 1-bit ** case means that every term of the OR clause is of the form ** "table.column=expr" for some single table. The one bit that is set ** will correspond to the common table. We still need to check to make ** sure the same column is used on all terms. The 2-bit case is when ** the all terms are of the form "table1.column=table2.column". It ** might be possible to form an IN operator with either table1.column ** or table2.column as the LHS if either is common to every term of ** the OR clause. ** ** Note that terms of the form "table.column1=table.column2" (the ** same table on both sizes of the ==) cannot be optimized. */ if( chngToIN ){ int okToChngToIN = 0; /* True if the conversion to IN is valid */ int iColumn = -1; /* Column index on lhs of IN operator */ int iCursor = -1; /* Table cursor common to all terms */ int j = 0; /* Loop counter */ /* Search for a table and column that appears on one side or the ** other of the == operator in every subterm. That table and column ** will be recorded in iCursor and iColumn. There might not be any ** such table and column. Set okToChngToIN if an appropriate table ** and column is found but leave okToChngToIN false if not found. */ for(j=0; j<2 && !okToChngToIN; j++){ pOrTerm = pOrWc->a; for(i=pOrWc->nTerm-1; i>=0; i--, pOrTerm++){ assert( pOrTerm->eOperator==WO_EQ ); pOrTerm->wtFlags &= ~TERM_OR_OK; if( pOrTerm->leftCursor==iCursor ){ /* This is the 2-bit case and we are on the second iteration and ** current term is from the first iteration. So skip this term. */ assert( j==1 ); continue; } if( (chngToIN & getMask(pMaskSet, pOrTerm->leftCursor))==0 ){ /* This term must be of the form t1.a==t2.b where t2 is in the ** chngToIN set but t1 is not. This term will be either preceeded ** or follwed by an inverted copy (t2.b==t1.a). Skip this term ** and use its inversion. */ testcase( pOrTerm->wtFlags & TERM_COPIED ); testcase( pOrTerm->wtFlags & TERM_VIRTUAL ); assert( pOrTerm->wtFlags & (TERM_COPIED|TERM_VIRTUAL) ); continue; } iColumn = pOrTerm->u.leftColumn; iCursor = pOrTerm->leftCursor; break; } if( i<0 ){ /* No candidate table+column was found. This can only occur ** on the second iteration */ assert( j==1 ); assert( (chngToIN&(chngToIN-1))==0 ); assert( chngToIN==getMask(pMaskSet, iCursor) ); break; } testcase( j==1 ); /* We have found a candidate table and column. Check to see if that ** table and column is common to every term in the OR clause */ okToChngToIN = 1; for(; i>=0 && okToChngToIN; i--, pOrTerm++){ assert( pOrTerm->eOperator==WO_EQ ); if( pOrTerm->leftCursor!=iCursor ){ pOrTerm->wtFlags &= ~TERM_OR_OK; }else if( pOrTerm->u.leftColumn!=iColumn ){ okToChngToIN = 0; }else{ int affLeft, affRight; /* If the right-hand side is also a column, then the affinities ** of both right and left sides must be such that no type ** conversions are required on the right. (Ticket #2249) */ affRight = sqlite3ExprAffinity(pOrTerm->pExpr->pRight); affLeft = sqlite3ExprAffinity(pOrTerm->pExpr->pLeft); if( affRight!=0 && affRight!=affLeft ){ okToChngToIN = 0; }else{ pOrTerm->wtFlags |= TERM_OR_OK; } } } } /* At this point, okToChngToIN is true if original pTerm satisfies ** case 1. In that case, construct a new virtual term that is ** pTerm converted into an IN operator. ** ** EV: R-00211-15100 */ if( okToChngToIN ){ Expr *pDup; /* A transient duplicate expression */ ExprList *pList = 0; /* The RHS of the IN operator */ Expr *pLeft = 0; /* The LHS of the IN operator */ Expr *pNew; /* The complete IN operator */ for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0; i--, pOrTerm++){ if( (pOrTerm->wtFlags & TERM_OR_OK)==0 ) continue; assert( pOrTerm->eOperator==WO_EQ ); assert( pOrTerm->leftCursor==iCursor ); assert( pOrTerm->u.leftColumn==iColumn ); pDup = sqlite3ExprDup(db, pOrTerm->pExpr->pRight, 0); pList = sqlite3ExprListAppend(pWC->pParse, pList, pDup); pLeft = pOrTerm->pExpr->pLeft; } assert( pLeft!=0 ); pDup = sqlite3ExprDup(db, pLeft, 0); pNew = sqlite3PExpr(pParse, TK_IN, pDup, 0, 0); if( pNew ){ int idxNew; transferJoinMarkings(pNew, pExpr); assert( !ExprHasProperty(pNew, EP_xIsSelect) ); pNew->x.pList = pList; idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC); testcase( idxNew==0 ); exprAnalyze(pSrc, pWC, idxNew); pTerm = &pWC->a[idxTerm]; pWC->a[idxNew].iParent = idxTerm; pTerm->nChild = 1; }else{ sqlite3ExprListDelete(db, pList); } pTerm->eOperator = WO_NOOP; /* case 1 trumps case 2 */ } } } #endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */ /* ** The input to this routine is an WhereTerm structure with only the ** "pExpr" field filled in. The job of this routine is to analyze the ** subexpression and populate all the other fields of the WhereTerm ** structure. ** ** If the expression is of the form "<expr> <op> X" it gets commuted ** to the standard form of "X <op> <expr>". ** ** If the expression is of the form "X <op> Y" where both X and Y are ** columns, then the original expression is unchanged and a new virtual ** term of the form "Y <op> X" is added to the WHERE clause and ** analyzed separately. The original term is marked with TERM_COPIED ** and the new term is marked with TERM_DYNAMIC (because it's pExpr ** needs to be freed with the WhereClause) and TERM_VIRTUAL (because it ** is a commuted copy of a prior term.) The original term has nChild=1 ** and the copy has idxParent set to the index of the original term. */ static void exprAnalyze( SrcList *pSrc, /* the FROM clause */ WhereClause *pWC, /* the WHERE clause */ int idxTerm /* Index of the term to be analyzed */ ){ WhereTerm *pTerm; /* The term to be analyzed */ WhereMaskSet *pMaskSet; /* Set of table index masks */ Expr *pExpr; /* The expression to be analyzed */ Bitmask prereqLeft; /* Prerequesites of the pExpr->pLeft */ Bitmask prereqAll; /* Prerequesites of pExpr */ Bitmask extraRight = 0; /* Extra dependencies on LEFT JOIN */ Expr *pStr1 = 0; /* RHS of LIKE/GLOB operator */ int isComplete = 0; /* RHS of LIKE/GLOB ends with wildcard */ int noCase = 0; /* LIKE/GLOB distinguishes case */ int op; /* Top-level operator. pExpr->op */ Parse *pParse = pWC->pParse; /* Parsing context */ sqlite3 *db = pParse->db; /* Database connection */ if( db->mallocFailed ){ return; } pTerm = &pWC->a[idxTerm]; pMaskSet = pWC->pMaskSet; pExpr = pTerm->pExpr; prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft); op = pExpr->op; if( op==TK_IN ){ assert( pExpr->pRight==0 ); if( ExprHasProperty(pExpr, EP_xIsSelect) ){ pTerm->prereqRight = exprSelectTableUsage(pMaskSet, pExpr->x.pSelect); }else{ pTerm->prereqRight = exprListTableUsage(pMaskSet, pExpr->x.pList); } }else if( op==TK_ISNULL ){ pTerm->prereqRight = 0; }else{ pTerm->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight); } prereqAll = exprTableUsage(pMaskSet, pExpr); if( ExprHasProperty(pExpr, EP_FromJoin) ){ Bitmask x = getMask(pMaskSet, pExpr->iRightJoinTable); prereqAll |= x; extraRight = x-1; /* ON clause terms may not be used with an index ** on left table of a LEFT JOIN. Ticket #3015 */ } pTerm->prereqAll = prereqAll; pTerm->leftCursor = -1; pTerm->iParent = -1; pTerm->eOperator = 0; if( allowedOp(op) && (pTerm->prereqRight & prereqLeft)==0 ){ Expr *pLeft = pExpr->pLeft; Expr *pRight = pExpr->pRight; if( pLeft->op==TK_COLUMN ){ pTerm->leftCursor = pLeft->iTable; pTerm->u.leftColumn = pLeft->iColumn; pTerm->eOperator = operatorMask(op); } if( pRight && pRight->op==TK_COLUMN ){ WhereTerm *pNew; Expr *pDup; if( pTerm->leftCursor>=0 ){ int idxNew; pDup = sqlite3ExprDup(db, pExpr, 0); if( db->mallocFailed ){ sqlite3ExprDelete(db, pDup); return; } idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC); if( idxNew==0 ) return; pNew = &pWC->a[idxNew]; pNew->iParent = idxTerm; pTerm = &pWC->a[idxTerm]; pTerm->nChild = 1; pTerm->wtFlags |= TERM_COPIED; }else{ pDup = pExpr; pNew = pTerm; } exprCommute(pParse, pDup); pLeft = pDup->pLeft; pNew->leftCursor = pLeft->iTable; pNew->u.leftColumn = pLeft->iColumn; testcase( (prereqLeft | extraRight) != prereqLeft ); pNew->prereqRight = prereqLeft | extraRight; pNew->prereqAll = prereqAll; pNew->eOperator = operatorMask(pDup->op); } } #ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION /* If a term is the BETWEEN operator, create two new virtual terms ** that define the range that the BETWEEN implements. For example: ** ** a BETWEEN b AND c ** ** is converted into: ** ** (a BETWEEN b AND c) AND (a>=b) AND (a<=c) ** ** The two new terms are added onto the end of the WhereClause object. ** The new terms are "dynamic" and are children of the original BETWEEN ** term. That means that if the BETWEEN term is coded, the children are ** skipped. Or, if the children are satisfied by an index, the original ** BETWEEN term is skipped. */ else if( pExpr->op==TK_BETWEEN && pWC->op==TK_AND ){ ExprList *pList = pExpr->x.pList; int i; static const u8 ops[] = {TK_GE, TK_LE}; assert( pList!=0 ); assert( pList->nExpr==2 ); for(i=0; i<2; i++){ Expr *pNewExpr; int idxNew; pNewExpr = sqlite3PExpr(pParse, ops[i], sqlite3ExprDup(db, pExpr->pLeft, 0), sqlite3ExprDup(db, pList->a[i].pExpr, 0), 0); idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC); testcase( idxNew==0 ); exprAnalyze(pSrc, pWC, idxNew); pTerm = &pWC->a[idxTerm]; pWC->a[idxNew].iParent = idxTerm; } pTerm->nChild = 2; } #endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */ #if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY) /* Analyze a term that is composed of two or more subterms connected by ** an OR operator. */ else if( pExpr->op==TK_OR ){ assert( pWC->op==TK_AND ); exprAnalyzeOrTerm(pSrc, pWC, idxTerm); pTerm = &pWC->a[idxTerm]; } #endif /* SQLITE_OMIT_OR_OPTIMIZATION */ #ifndef SQLITE_OMIT_LIKE_OPTIMIZATION /* Add constraints to reduce the search space on a LIKE or GLOB ** operator. ** ** A like pattern of the form "x LIKE 'abc%'" is changed into constraints ** ** x>='abc' AND x<'abd' AND x LIKE 'abc%' ** ** The last character of the prefix "abc" is incremented to form the ** termination condition "abd". */ if( pWC->op==TK_AND && isLikeOrGlob(pParse, pExpr, &pStr1, &isComplete, &noCase) ){ Expr *pLeft; /* LHS of LIKE/GLOB operator */ Expr *pStr2; /* Copy of pStr1 - RHS of LIKE/GLOB operator */ Expr *pNewExpr1; Expr *pNewExpr2; int idxNew1; int idxNew2; CollSeq *pColl; /* Collating sequence to use */ pLeft = pExpr->x.pList->a[1].pExpr; pStr2 = sqlite3ExprDup(db, pStr1, 0); if( !db->mallocFailed ){ u8 c, *pC; /* Last character before the first wildcard */ pC = (u8*)&pStr2->u.zToken[sqlite3Strlen30(pStr2->u.zToken)-1]; c = *pC; if( noCase ){ /* The point is to increment the last character before the first ** wildcard. But if we increment '@', that will push it into the ** alphabetic range where case conversions will mess up the ** inequality. To avoid this, make sure to also run the full ** LIKE on all candidate expressions by clearing the isComplete flag */ if( c=='A'-1 ) isComplete = 0; /* EV: R-64339-08207 */ c = sqlite3UpperToLower[c]; } *pC = c + 1; } pColl = sqlite3FindCollSeq(db, SQLITE_UTF8, noCase ? "NOCASE" : "BINARY",0); pNewExpr1 = sqlite3PExpr(pParse, TK_GE, sqlite3ExprSetColl(sqlite3ExprDup(db,pLeft,0), pColl), pStr1, 0); idxNew1 = whereClauseInsert(pWC, pNewExpr1, TERM_VIRTUAL|TERM_DYNAMIC); testcase( idxNew1==0 ); exprAnalyze(pSrc, pWC, idxNew1); pNewExpr2 = sqlite3PExpr(pParse, TK_LT, sqlite3ExprSetColl(sqlite3ExprDup(db,pLeft,0), pColl), pStr2, 0); idxNew2 = whereClauseInsert(pWC, pNewExpr2, TERM_VIRTUAL|TERM_DYNAMIC); testcase( idxNew2==0 ); exprAnalyze(pSrc, pWC, idxNew2); pTerm = &pWC->a[idxTerm]; if( isComplete ){ pWC->a[idxNew1].iParent = idxTerm; pWC->a[idxNew2].iParent = idxTerm; pTerm->nChild = 2; } } #endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */ #ifndef SQLITE_OMIT_VIRTUALTABLE /* Add a WO_MATCH auxiliary term to the constraint set if the ** current expression is of the form: column MATCH expr. ** This information is used by the xBestIndex methods of ** virtual tables. The native query optimizer does not attempt ** to do anything with MATCH functions. */ if( isMatchOfColumn(pExpr) ){ int idxNew; Expr *pRight, *pLeft; WhereTerm *pNewTerm; Bitmask prereqColumn, prereqExpr; pRight = pExpr->x.pList->a[0].pExpr; pLeft = pExpr->x.pList->a[1].pExpr; prereqExpr = exprTableUsage(pMaskSet, pRight); prereqColumn = exprTableUsage(pMaskSet, pLeft); if( (prereqExpr & prereqColumn)==0 ){ Expr *pNewExpr; pNewExpr = sqlite3PExpr(pParse, TK_MATCH, 0, sqlite3ExprDup(db, pRight, 0), 0); idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC); testcase( idxNew==0 ); pNewTerm = &pWC->a[idxNew]; pNewTerm->prereqRight = prereqExpr; pNewTerm->leftCursor = pLeft->iTable; pNewTerm->u.leftColumn = pLeft->iColumn; pNewTerm->eOperator = WO_MATCH; pNewTerm->iParent = idxTerm; pTerm = &pWC->a[idxTerm]; pTerm->nChild = 1; pTerm->wtFlags |= TERM_COPIED; pNewTerm->prereqAll = pTerm->prereqAll; } } #endif /* SQLITE_OMIT_VIRTUALTABLE */ #ifdef SQLITE_ENABLE_STAT2 /* When sqlite_stat2 histogram data is available an operator of the ** form "x IS NOT NULL" can sometimes be evaluated more efficiently ** as "x>NULL" if x is not an INTEGER PRIMARY KEY. So construct a ** virtual term of that form. ** ** Note that the virtual term must be tagged with TERM_VNULL. This ** TERM_VNULL tag will suppress the not-null check at the beginning ** of the loop. Without the TERM_VNULL flag, the not-null check at ** the start of the loop will prevent any results from being returned. */ if( pExpr->op==TK_NOTNULL && pExpr->pLeft->op==TK_COLUMN && pExpr->pLeft->iColumn>=0 ){ Expr *pNewExpr; Expr *pLeft = pExpr->pLeft; int idxNew; WhereTerm *pNewTerm; pNewExpr = sqlite3PExpr(pParse, TK_GT, sqlite3ExprDup(db, pLeft, 0), sqlite3PExpr(pParse, TK_NULL, 0, 0, 0), 0); idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC|TERM_VNULL); if( idxNew ){ pNewTerm = &pWC->a[idxNew]; pNewTerm->prereqRight = 0; pNewTerm->leftCursor = pLeft->iTable; pNewTerm->u.leftColumn = pLeft->iColumn; pNewTerm->eOperator = WO_GT; pNewTerm->iParent = idxTerm; pTerm = &pWC->a[idxTerm]; pTerm->nChild = 1; pTerm->wtFlags |= TERM_COPIED; pNewTerm->prereqAll = pTerm->prereqAll; } } #endif /* SQLITE_ENABLE_STAT2 */ /* Prevent ON clause terms of a LEFT JOIN from being used to drive ** an index for tables to the left of the join. */ pTerm->prereqRight |= extraRight; } /* ** Return TRUE if any of the expressions in pList->a[iFirst...] contain ** a reference to any table other than the iBase table. */ static int referencesOtherTables( ExprList *pList, /* Search expressions in ths list */ WhereMaskSet *pMaskSet, /* Mapping from tables to bitmaps */ int iFirst, /* Be searching with the iFirst-th expression */ int iBase /* Ignore references to this table */ ){ Bitmask allowed = ~getMask(pMaskSet, iBase); while( iFirst<pList->nExpr ){ if( (exprTableUsage(pMaskSet, pList->a[iFirst++].pExpr)&allowed)!=0 ){ return 1; } } return 0; } /* ** This routine decides if pIdx can be used to satisfy the ORDER BY ** clause. If it can, it returns 1. If pIdx cannot satisfy the ** ORDER BY clause, this routine returns 0. ** ** pOrderBy is an ORDER BY clause from a SELECT statement. pTab is the ** left-most table in the FROM clause of that same SELECT statement and ** the table has a cursor number of "base". pIdx is an index on pTab. ** ** nEqCol is the number of columns of pIdx that are used as equality ** constraints. Any of these columns may be missing from the ORDER BY ** clause and the match can still be a success. ** ** All terms of the ORDER BY that match against the index must be either ** ASC or DESC. (Terms of the ORDER BY clause past the end of a UNIQUE ** index do not need to satisfy this constraint.) The *pbRev value is ** set to 1 if the ORDER BY clause is all DESC and it is set to 0 if ** the ORDER BY clause is all ASC. */ static int isSortingIndex( Parse *pParse, /* Parsing context */ WhereMaskSet *pMaskSet, /* Mapping from table cursor numbers to bitmaps */ Index *pIdx, /* The index we are testing */ int base, /* Cursor number for the table to be sorted */ ExprList *pOrderBy, /* The ORDER BY clause */ int nEqCol, /* Number of index columns with == constraints */ int wsFlags, /* Index usages flags */ int *pbRev /* Set to 1 if ORDER BY is DESC */ ){ int i, j; /* Loop counters */ int sortOrder = 0; /* XOR of index and ORDER BY sort direction */ int nTerm; /* Number of ORDER BY terms */ struct ExprList_item *pTerm; /* A term of the ORDER BY clause */ sqlite3 *db = pParse->db; assert( pOrderBy!=0 ); nTerm = pOrderBy->nExpr; assert( nTerm>0 ); /* Argument pIdx must either point to a 'real' named index structure, ** or an index structure allocated on the stack by bestBtreeIndex() to ** represent the rowid index that is part of every table. */ assert( pIdx->zName || (pIdx->nColumn==1 && pIdx->aiColumn[0]==-1) ); /* Match terms of the ORDER BY clause against columns of ** the index. ** ** Note that indices have pIdx->nColumn regular columns plus ** one additional column containing the rowid. The rowid column ** of the index is also allowed to match against the ORDER BY ** clause. */ for(i=j=0, pTerm=pOrderBy->a; j<nTerm && i<=pIdx->nColumn; i++){ Expr *pExpr; /* The expression of the ORDER BY pTerm */ CollSeq *pColl; /* The collating sequence of pExpr */ int termSortOrder; /* Sort order for this term */ int iColumn; /* The i-th column of the index. -1 for rowid */ int iSortOrder; /* 1 for DESC, 0 for ASC on the i-th index term */ const char *zColl; /* Name of the collating sequence for i-th index term */ pExpr = pTerm->pExpr; if( pExpr->op!=TK_COLUMN || pExpr->iTable!=base ){ /* Can not use an index sort on anything that is not a column in the ** left-most table of the FROM clause */ break; } pColl = sqlite3ExprCollSeq(pParse, pExpr); if( !pColl ){ pColl = db->pDfltColl; } if( pIdx->zName && i<pIdx->nColumn ){ iColumn = pIdx->aiColumn[i]; if( iColumn==pIdx->pTable->iPKey ){ iColumn = -1; } iSortOrder = pIdx->aSortOrder[i]; zColl = pIdx->azColl[i]; }else{ iColumn = -1; iSortOrder = 0; zColl = pColl->zName; } if( pExpr->iColumn!=iColumn || sqlite3StrICmp(pColl->zName, zColl) ){ /* Term j of the ORDER BY clause does not match column i of the index */ if( i<nEqCol ){ /* If an index column that is constrained by == fails to match an ** ORDER BY term, that is OK. Just ignore that column of the index */ continue; }else if( i==pIdx->nColumn ){ /* Index column i is the rowid. All other terms match. */ break; }else{ /* If an index column fails to match and is not constrained by == ** then the index cannot satisfy the ORDER BY constraint. */ return 0; } } assert( pIdx->aSortOrder!=0 || iColumn==-1 ); assert( pTerm->sortOrder==0 || pTerm->sortOrder==1 ); assert( iSortOrder==0 || iSortOrder==1 ); termSortOrder = iSortOrder ^ pTerm->sortOrder; if( i>nEqCol ){ if( termSortOrder!=sortOrder ){ /* Indices can only be used if all ORDER BY terms past the ** equality constraints are all either DESC or ASC. */ return 0; } }else{ sortOrder = termSortOrder; } j++; pTerm++; if( iColumn<0 && !referencesOtherTables(pOrderBy, pMaskSet, j, base) ){ /* If the indexed column is the primary key and everything matches ** so far and none of the ORDER BY terms to the right reference other ** tables in the join, then we are assured that the index can be used ** to sort because the primary key is unique and so none of the other ** columns will make any difference */ j = nTerm; } } *pbRev = sortOrder!=0; if( j>=nTerm ){ /* All terms of the ORDER BY clause are covered by this index so ** this index can be used for sorting. */ return 1; } if( pIdx->onError!=OE_None && i==pIdx->nColumn && (wsFlags & WHERE_COLUMN_NULL)==0 && !referencesOtherTables(pOrderBy, pMaskSet, j, base) ){ /* All terms of this index match some prefix of the ORDER BY clause ** and the index is UNIQUE and no terms on the tail of the ORDER BY ** clause reference other tables in a join. If this is all true then ** the order by clause is superfluous. Not that if the matching ** condition is IS NULL then the result is not necessarily unique ** even on a UNIQUE index, so disallow those cases. */ return 1; } return 0; } /* ** Prepare a crude estimate of the logarithm of the input value. ** The results need not be exact. This is only used for estimating ** the total cost of performing operations with O(logN) or O(NlogN) ** complexity. Because N is just a guess, it is no great tragedy if ** logN is a little off. */ static double estLog(double N){ double logN = 1; double x = 10; while( N>x ){ logN += 1; x *= 10; } return logN; } /* ** Two routines for printing the content of an sqlite3_index_info ** structure. Used for testing and debugging only. If neither ** SQLITE_TEST or SQLITE_DEBUG are defined, then these routines ** are no-ops. */ #if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(SQLITE_DEBUG) static void TRACE_IDX_INPUTS(sqlite3_index_info *p){ int i; if( !sqlite3WhereTrace ) return; for(i=0; i<p->nConstraint; i++){ sqlite3DebugPrintf(" constraint[%d]: col=%d termid=%d op=%d usabled=%d\n", i, p->aConstraint[i].iColumn, p->aConstraint[i].iTermOffset, p->aConstraint[i].op, p->aConstraint[i].usable); } for(i=0; i<p->nOrderBy; i++){ sqlite3DebugPrintf(" orderby[%d]: col=%d desc=%d\n", i, p->aOrderBy[i].iColumn, p->aOrderBy[i].desc); } } static void TRACE_IDX_OUTPUTS(sqlite3_index_info *p){ int i; if( !sqlite3WhereTrace ) return; for(i=0; i<p->nConstraint; i++){ sqlite3DebugPrintf(" usage[%d]: argvIdx=%d omit=%d\n", i, p->aConstraintUsage[i].argvIndex, p->aConstraintUsage[i].omit); } sqlite3DebugPrintf(" idxNum=%d\n", p->idxNum); sqlite3DebugPrintf(" idxStr=%s\n", p->idxStr); sqlite3DebugPrintf(" orderByConsumed=%d\n", p->orderByConsumed); sqlite3DebugPrintf(" estimatedCost=%g\n", p->estimatedCost); } #else #define TRACE_IDX_INPUTS(A) #define TRACE_IDX_OUTPUTS(A) #endif /* ** Required because bestIndex() is called by bestOrClauseIndex() */ static void bestIndex( Parse*, WhereClause*, struct SrcList_item*, Bitmask, Bitmask, ExprList*, WhereCost*); /* ** This routine attempts to find an scanning strategy that can be used ** to optimize an 'OR' expression that is part of a WHERE clause. ** ** The table associated with FROM clause term pSrc may be either a ** regular B-Tree table or a virtual table. */ static void bestOrClauseIndex( Parse *pParse, /* The parsing context */ WhereClause *pWC, /* The WHERE clause */ struct SrcList_item *pSrc, /* The FROM clause term to search */ Bitmask notReady, /* Mask of cursors not available for indexing */ Bitmask notValid, /* Cursors not available for any purpose */ ExprList *pOrderBy, /* The ORDER BY clause */ WhereCost *pCost /* Lowest cost query plan */ ){ #ifndef SQLITE_OMIT_OR_OPTIMIZATION const int iCur = pSrc->iCursor; /* The cursor of the table to be accessed */ const Bitmask maskSrc = getMask(pWC->pMaskSet, iCur); /* Bitmask for pSrc */ WhereTerm * const pWCEnd = &pWC->a[pWC->nTerm]; /* End of pWC->a[] */ WhereTerm *pTerm; /* A single term of the WHERE clause */ /* No OR-clause optimization allowed if the INDEXED BY or NOT INDEXED clauses ** are used */ if( pSrc->notIndexed || pSrc->pIndex!=0 ){ return; } /* Search the WHERE clause terms for a usable WO_OR term. */ for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){ if( pTerm->eOperator==WO_OR && ((pTerm->prereqAll & ~maskSrc) & notReady)==0 && (pTerm->u.pOrInfo->indexable & maskSrc)!=0 ){ WhereClause * const pOrWC = &pTerm->u.pOrInfo->wc; WhereTerm * const pOrWCEnd = &pOrWC->a[pOrWC->nTerm]; WhereTerm *pOrTerm; int flags = WHERE_MULTI_OR; double rTotal = 0; double nRow = 0; Bitmask used = 0; for(pOrTerm=pOrWC->a; pOrTerm<pOrWCEnd; pOrTerm++){ WhereCost sTermCost; WHERETRACE(("... Multi-index OR testing for term %d of %d....\n", (pOrTerm - pOrWC->a), (pTerm - pWC->a) )); if( pOrTerm->eOperator==WO_AND ){ WhereClause *pAndWC = &pOrTerm->u.pAndInfo->wc; bestIndex(pParse, pAndWC, pSrc, notReady, notValid, 0, &sTermCost); }else if( pOrTerm->leftCursor==iCur ){ WhereClause tempWC; tempWC.pParse = pWC->pParse; tempWC.pMaskSet = pWC->pMaskSet; tempWC.op = TK_AND; tempWC.a = pOrTerm; tempWC.nTerm = 1; bestIndex(pParse, &tempWC, pSrc, notReady, notValid, 0, &sTermCost); }else{ continue; } rTotal += sTermCost.rCost; nRow += sTermCost.plan.nRow; used |= sTermCost.used; if( rTotal>=pCost->rCost ) break; } /* If there is an ORDER BY clause, increase the scan cost to account ** for the cost of the sort. */ if( pOrderBy!=0 ){ WHERETRACE(("... sorting increases OR cost %.9g to %.9g\n", rTotal, rTotal+nRow*estLog(nRow))); rTotal += nRow*estLog(nRow); } /* If the cost of scanning using this OR term for optimization is ** less than the current cost stored in pCost, replace the contents ** of pCost. */ WHERETRACE(("... multi-index OR cost=%.9g nrow=%.9g\n", rTotal, nRow)); if( rTotal<pCost->rCost ){ pCost->rCost = rTotal; pCost->used = used; pCost->plan.nRow = nRow; pCost->plan.wsFlags = flags; pCost->plan.u.pTerm = pTerm; } } } #endif /* SQLITE_OMIT_OR_OPTIMIZATION */ } #ifndef SQLITE_OMIT_AUTOMATIC_INDEX /* ** Return TRUE if the WHERE clause term pTerm is of a form where it ** could be used with an index to access pSrc, assuming an appropriate ** index existed. */ static int termCanDriveIndex( WhereTerm *pTerm, /* WHERE clause term to check */ struct SrcList_item *pSrc, /* Table we are trying to access */ Bitmask notReady /* Tables in outer loops of the join */ ){ char aff; if( pTerm->leftCursor!=pSrc->iCursor ) return 0; if( pTerm->eOperator!=WO_EQ ) return 0; if( (pTerm->prereqRight & notReady)!=0 ) return 0; aff = pSrc->pTab->aCol[pTerm->u.leftColumn].affinity; if( !sqlite3IndexAffinityOk(pTerm->pExpr, aff) ) return 0; return 1; } #endif #ifndef SQLITE_OMIT_AUTOMATIC_INDEX /* ** If the query plan for pSrc specified in pCost is a full table scan ** and indexing is allows (if there is no NOT INDEXED clause) and it ** possible to construct a transient index that would perform better ** than a full table scan even when the cost of constructing the index ** is taken into account, then alter the query plan to use the ** transient index. */ static void bestAutomaticIndex( Parse *pParse, /* The parsing context */ WhereClause *pWC, /* The WHERE clause */ struct SrcList_item *pSrc, /* The FROM clause term to search */ Bitmask notReady, /* Mask of cursors that are not available */ WhereCost *pCost /* Lowest cost query plan */ ){ double nTableRow; /* Rows in the input table */ double logN; /* log(nTableRow) */ double costTempIdx; /* per-query cost of the transient index */ WhereTerm *pTerm; /* A single term of the WHERE clause */ WhereTerm *pWCEnd; /* End of pWC->a[] */ Table *pTable; /* Table tht might be indexed */ if( (pParse->db->flags & SQLITE_AutoIndex)==0 ){ /* Automatic indices are disabled at run-time */ return; } if( (pCost->plan.wsFlags & WHERE_NOT_FULLSCAN)!=0 ){ /* We already have some kind of index in use for this query. */ return; } if( pSrc->notIndexed ){ /* The NOT INDEXED clause appears in the SQL. */ return; } assert( pParse->nQueryLoop >= (double)1 ); pTable = pSrc->pTab; nTableRow = pTable->nRowEst; logN = estLog(nTableRow); costTempIdx = 2*logN*(nTableRow/pParse->nQueryLoop + 1); if( costTempIdx>=pCost->rCost ){ /* The cost of creating the transient table would be greater than ** doing the full table scan */ return; } /* Search for any equality comparison term */ pWCEnd = &pWC->a[pWC->nTerm]; for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){ if( termCanDriveIndex(pTerm, pSrc, notReady) ){ WHERETRACE(("auto-index reduces cost from %.1f to %.1f\n", pCost->rCost, costTempIdx)); pCost->rCost = costTempIdx; pCost->plan.nRow = logN + 1; pCost->plan.wsFlags = WHERE_TEMP_INDEX; pCost->used = pTerm->prereqRight; break; } } } #else # define bestAutomaticIndex(A,B,C,D,E) /* no-op */ #endif /* SQLITE_OMIT_AUTOMATIC_INDEX */ #ifndef SQLITE_OMIT_AUTOMATIC_INDEX /* ** Generate code to construct the Index object for an automatic index ** and to set up the WhereLevel object pLevel so that the code generator ** makes use of the automatic index. */ static void constructAutomaticIndex( Parse *pParse, /* The parsing context */ WhereClause *pWC, /* The WHERE clause */ struct SrcList_item *pSrc, /* The FROM clause term to get the next index */ Bitmask notReady, /* Mask of cursors that are not available */ WhereLevel *pLevel /* Write new index here */ ){ int nColumn; /* Number of columns in the constructed index */ WhereTerm *pTerm; /* A single term of the WHERE clause */ WhereTerm *pWCEnd; /* End of pWC->a[] */ int nByte; /* Byte of memory needed for pIdx */ Index *pIdx; /* Object describing the transient index */ Vdbe *v; /* Prepared statement under construction */ int regIsInit; /* Register set by initialization */ int addrInit; /* Address of the initialization bypass jump */ Table *pTable; /* The table being indexed */ KeyInfo *pKeyinfo; /* Key information for the index */ int addrTop; /* Top of the index fill loop */ int regRecord; /* Register holding an index record */ int n; /* Column counter */ int i; /* Loop counter */ int mxBitCol; /* Maximum column in pSrc->colUsed */ CollSeq *pColl; /* Collating sequence to on a column */ Bitmask idxCols; /* Bitmap of columns used for indexing */ Bitmask extraCols; /* Bitmap of additional columns */ /* Generate code to skip over the creation and initialization of the ** transient index on 2nd and subsequent iterations of the loop. */ v = pParse->pVdbe; assert( v!=0 ); regIsInit = ++pParse->nMem; addrInit = sqlite3VdbeAddOp1(v, OP_If, regIsInit); sqlite3VdbeAddOp2(v, OP_Integer, 1, regIsInit); /* Count the number of columns that will be added to the index ** and used to match WHERE clause constraints */ nColumn = 0; pTable = pSrc->pTab; pWCEnd = &pWC->a[pWC->nTerm]; idxCols = 0; for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){ if( termCanDriveIndex(pTerm, pSrc, notReady) ){ int iCol = pTerm->u.leftColumn; Bitmask cMask = iCol>=BMS ? ((Bitmask)1)<<(BMS-1) : ((Bitmask)1)<<iCol; testcase( iCol==BMS ); testcase( iCol==BMS-1 ); if( (idxCols & cMask)==0 ){ nColumn++; idxCols |= cMask; } } } assert( nColumn>0 ); pLevel->plan.nEq = nColumn; /* Count the number of additional columns needed to create a ** covering index. A "covering index" is an index that contains all ** columns that are needed by the query. With a covering index, the ** original table never needs to be accessed. Automatic indices must ** be a covering index because the index will not be updated if the ** original table changes and the index and table cannot both be used ** if they go out of sync. */ extraCols = pSrc->colUsed & (~idxCols | (((Bitmask)1)<<(BMS-1))); mxBitCol = (pTable->nCol >= BMS-1) ? BMS-1 : pTable->nCol; testcase( pTable->nCol==BMS-1 ); testcase( pTable->nCol==BMS-2 ); for(i=0; i<mxBitCol; i++){ if( extraCols & (((Bitmask)1)<<i) ) nColumn++; } if( pSrc->colUsed & (((Bitmask)1)<<(BMS-1)) ){ nColumn += pTable->nCol - BMS + 1; } pLevel->plan.wsFlags |= WHERE_COLUMN_EQ | WHERE_IDX_ONLY | WO_EQ; /* Construct the Index object to describe this index */ nByte = sizeof(Index); nByte += nColumn*sizeof(int); /* Index.aiColumn */ nByte += nColumn*sizeof(char*); /* Index.azColl */ nByte += nColumn; /* Index.aSortOrder */ pIdx = sqlite3DbMallocZero(pParse->db, nByte); if( pIdx==0 ) return; pLevel->plan.u.pIdx = pIdx; pIdx->azColl = (char**)&pIdx[1]; pIdx->aiColumn = (int*)&pIdx->azColl[nColumn]; pIdx->aSortOrder = (u8*)&pIdx->aiColumn[nColumn]; pIdx->zName = "auto-index"; pIdx->nColumn = nColumn; pIdx->pTable = pTable; n = 0; idxCols = 0; for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){ if( termCanDriveIndex(pTerm, pSrc, notReady) ){ int iCol = pTerm->u.leftColumn; Bitmask cMask = iCol>=BMS ? ((Bitmask)1)<<(BMS-1) : ((Bitmask)1)<<iCol; if( (idxCols & cMask)==0 ){ Expr *pX = pTerm->pExpr; idxCols |= cMask; pIdx->aiColumn[n] = pTerm->u.leftColumn; pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight); pIdx->azColl[n] = ALWAYS(pColl) ? pColl->zName : "BINARY"; n++; } } } assert( (u32)n==pLevel->plan.nEq ); /* Add additional columns needed to make the automatic index into ** a covering index */ for(i=0; i<mxBitCol; i++){ if( extraCols & (((Bitmask)1)<<i) ){ pIdx->aiColumn[n] = i; pIdx->azColl[n] = "BINARY"; n++; } } if( pSrc->colUsed & (((Bitmask)1)<<(BMS-1)) ){ for(i=BMS-1; i<pTable->nCol; i++){ pIdx->aiColumn[n] = i; pIdx->azColl[n] = "BINARY"; n++; } } assert( n==nColumn ); /* Create the automatic index */ pKeyinfo = sqlite3IndexKeyinfo(pParse, pIdx); assert( pLevel->iIdxCur>=0 ); sqlite3VdbeAddOp4(v, OP_OpenAutoindex, pLevel->iIdxCur, nColumn+1, 0, (char*)pKeyinfo, P4_KEYINFO_HANDOFF); VdbeComment((v, "for %s", pTable->zName)); /* Fill the automatic index with content */ addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, pLevel->iTabCur); regRecord = sqlite3GetTempReg(pParse); sqlite3GenerateIndexKey(pParse, pIdx, pLevel->iTabCur, regRecord, 1); sqlite3VdbeAddOp2(v, OP_IdxInsert, pLevel->iIdxCur, regRecord); sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT); sqlite3VdbeAddOp2(v, OP_Next, pLevel->iTabCur, addrTop+1); sqlite3VdbeChangeP5(v, SQLITE_STMTSTATUS_AUTOINDEX); sqlite3VdbeJumpHere(v, addrTop); sqlite3ReleaseTempReg(pParse, regRecord); /* Jump here when skipping the initialization */ sqlite3VdbeJumpHere(v, addrInit); } #endif /* SQLITE_OMIT_AUTOMATIC_INDEX */ #ifndef SQLITE_OMIT_VIRTUALTABLE /* ** Allocate and populate an sqlite3_index_info structure. It is the ** responsibility of the caller to eventually release the structure ** by passing the pointer returned by this function to sqlite3_free(). */ static sqlite3_index_info *allocateIndexInfo( Parse *pParse, WhereClause *pWC, struct SrcList_item *pSrc, ExprList *pOrderBy ){ int i, j; int nTerm; struct sqlite3_index_constraint *pIdxCons; struct sqlite3_index_orderby *pIdxOrderBy; struct sqlite3_index_constraint_usage *pUsage; WhereTerm *pTerm; int nOrderBy; sqlite3_index_info *pIdxInfo; WHERETRACE(("Recomputing index info for %s...\n", pSrc->pTab->zName)); /* Count the number of possible WHERE clause constraints referring ** to this virtual table */ for(i=nTerm=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){ if( pTerm->leftCursor != pSrc->iCursor ) continue; assert( (pTerm->eOperator&(pTerm->eOperator-1))==0 ); testcase( pTerm->eOperator==WO_IN ); testcase( pTerm->eOperator==WO_ISNULL ); if( pTerm->eOperator & (WO_IN|WO_ISNULL) ) continue; nTerm++; } /* If the ORDER BY clause contains only columns in the current ** virtual table then allocate space for the aOrderBy part of ** the sqlite3_index_info structure. */ nOrderBy = 0; if( pOrderBy ){ for(i=0; i<pOrderBy->nExpr; i++){ Expr *pExpr = pOrderBy->a[i].pExpr; if( pExpr->op!=TK_COLUMN || pExpr->iTable!=pSrc->iCursor ) break; } if( i==pOrderBy->nExpr ){ nOrderBy = pOrderBy->nExpr; } } /* Allocate the sqlite3_index_info structure */ pIdxInfo = sqlite3DbMallocZero(pParse->db, sizeof(*pIdxInfo) + (sizeof(*pIdxCons) + sizeof(*pUsage))*nTerm + sizeof(*pIdxOrderBy)*nOrderBy ); if( pIdxInfo==0 ){ sqlite3ErrorMsg(pParse, "out of memory"); /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */ return 0; } /* Initialize the structure. The sqlite3_index_info structure contains ** many fields that are declared "const" to prevent xBestIndex from ** changing them. We have to do some funky casting in order to ** initialize those fields. */ pIdxCons = (struct sqlite3_index_constraint*)&pIdxInfo[1]; pIdxOrderBy = (struct sqlite3_index_orderby*)&pIdxCons[nTerm]; pUsage = (struct sqlite3_index_constraint_usage*)&pIdxOrderBy[nOrderBy]; *(int*)&pIdxInfo->nConstraint = nTerm; *(int*)&pIdxInfo->nOrderBy = nOrderBy; *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint = pIdxCons; *(struct sqlite3_index_orderby**)&pIdxInfo->aOrderBy = pIdxOrderBy; *(struct sqlite3_index_constraint_usage**)&pIdxInfo->aConstraintUsage = pUsage; for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){ if( pTerm->leftCursor != pSrc->iCursor ) continue; assert( (pTerm->eOperator&(pTerm->eOperator-1))==0 ); testcase( pTerm->eOperator==WO_IN ); testcase( pTerm->eOperator==WO_ISNULL ); if( pTerm->eOperator & (WO_IN|WO_ISNULL) ) continue; pIdxCons[j].iColumn = pTerm->u.leftColumn; pIdxCons[j].iTermOffset = i; pIdxCons[j].op = (u8)pTerm->eOperator; /* The direct assignment in the previous line is possible only because ** the WO_ and SQLITE_INDEX_CONSTRAINT_ codes are identical. The ** following asserts verify this fact. */ assert( WO_EQ==SQLITE_INDEX_CONSTRAINT_EQ ); assert( WO_LT==SQLITE_INDEX_CONSTRAINT_LT ); assert( WO_LE==SQLITE_INDEX_CONSTRAINT_LE ); assert( WO_GT==SQLITE_INDEX_CONSTRAINT_GT ); assert( WO_GE==SQLITE_INDEX_CONSTRAINT_GE ); assert( WO_MATCH==SQLITE_INDEX_CONSTRAINT_MATCH ); assert( pTerm->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE|WO_MATCH) ); j++; } for(i=0; i<nOrderBy; i++){ Expr *pExpr = pOrderBy->a[i].pExpr; pIdxOrderBy[i].iColumn = pExpr->iColumn; pIdxOrderBy[i].desc = pOrderBy->a[i].sortOrder; } return pIdxInfo; } /* ** The table object reference passed as the second argument to this function ** must represent a virtual table. This function invokes the xBestIndex() ** method of the virtual table with the sqlite3_index_info pointer passed ** as the argument. ** ** If an error occurs, pParse is populated with an error message and a ** non-zero value is returned. Otherwise, 0 is returned and the output ** part of the sqlite3_index_info structure is left populated. ** ** Whether or not an error is returned, it is the responsibility of the ** caller to eventually free p->idxStr if p->needToFreeIdxStr indicates ** that this is required. */ static int vtabBestIndex(Parse *pParse, Table *pTab, sqlite3_index_info *p){ sqlite3_vtab *pVtab = sqlite3GetVTable(pParse->db, pTab)->pVtab; int i; int rc; WHERETRACE(("xBestIndex for %s\n", pTab->zName)); TRACE_IDX_INPUTS(p); rc = pVtab->pModule->xBestIndex(pVtab, p); TRACE_IDX_OUTPUTS(p); if( rc!=SQLITE_OK ){ if( rc==SQLITE_NOMEM ){ pParse->db->mallocFailed = 1; }else if( !pVtab->zErrMsg ){ sqlite3ErrorMsg(pParse, "%s", sqlite3ErrStr(rc)); }else{ sqlite3ErrorMsg(pParse, "%s", pVtab->zErrMsg); } } sqlite3_free(pVtab->zErrMsg); pVtab->zErrMsg = 0; for(i=0; i<p->nConstraint; i++){ if( !p->aConstraint[i].usable && p->aConstraintUsage[i].argvIndex>0 ){ sqlite3ErrorMsg(pParse, "table %s: xBestIndex returned an invalid plan", pTab->zName); } } return pParse->nErr; } /* ** Compute the best index for a virtual table. ** ** The best index is computed by the xBestIndex method of the virtual ** table module. This routine is really just a wrapper that sets up ** the sqlite3_index_info structure that is used to communicate with ** xBestIndex. ** ** In a join, this routine might be called multiple times for the ** same virtual table. The sqlite3_index_info structure is created ** and initialized on the first invocation and reused on all subsequent ** invocations. The sqlite3_index_info structure is also used when ** code is generated to access the virtual table. The whereInfoDelete() ** routine takes care of freeing the sqlite3_index_info structure after ** everybody has finished with it. */ static void bestVirtualIndex( Parse *pParse, /* The parsing context */ WhereClause *pWC, /* The WHERE clause */ struct SrcList_item *pSrc, /* The FROM clause term to search */ Bitmask notReady, /* Mask of cursors not available for index */ Bitmask notValid, /* Cursors not valid for any purpose */ ExprList *pOrderBy, /* The order by clause */ WhereCost *pCost, /* Lowest cost query plan */ sqlite3_index_info **ppIdxInfo /* Index information passed to xBestIndex */ ){ Table *pTab = pSrc->pTab; sqlite3_index_info *pIdxInfo; struct sqlite3_index_constraint *pIdxCons; struct sqlite3_index_constraint_usage *pUsage; WhereTerm *pTerm; int i, j; int nOrderBy; double rCost; /* Make sure wsFlags is initialized to some sane value. Otherwise, if the ** malloc in allocateIndexInfo() fails and this function returns leaving ** wsFlags in an uninitialized state, the caller may behave unpredictably. */ memset(pCost, 0, sizeof(*pCost)); pCost->plan.wsFlags = WHERE_VIRTUALTABLE; /* If the sqlite3_index_info structure has not been previously ** allocated and initialized, then allocate and initialize it now. */ pIdxInfo = *ppIdxInfo; if( pIdxInfo==0 ){ *ppIdxInfo = pIdxInfo = allocateIndexInfo(pParse, pWC, pSrc, pOrderBy); } if( pIdxInfo==0 ){ return; } /* At this point, the sqlite3_index_info structure that pIdxInfo points ** to will have been initialized, either during the current invocation or ** during some prior invocation. Now we just have to customize the ** details of pIdxInfo for the current invocation and pass it to ** xBestIndex. */ /* The module name must be defined. Also, by this point there must ** be a pointer to an sqlite3_vtab structure. Otherwise ** sqlite3ViewGetColumnNames() would have picked up the error. */ assert( pTab->azModuleArg && pTab->azModuleArg[0] ); assert( sqlite3GetVTable(pParse->db, pTab) ); /* Set the aConstraint[].usable fields and initialize all ** output variables to zero. ** ** aConstraint[].usable is true for constraints where the right-hand ** side contains only references to tables to the left of the current ** table. In other words, if the constraint is of the form: ** ** column = expr ** ** and we are evaluating a join, then the constraint on column is ** only valid if all tables referenced in expr occur to the left ** of the table containing column. ** ** The aConstraints[] array contains entries for all constraints ** on the current table. That way we only have to compute it once ** even though we might try to pick the best index multiple times. ** For each attempt at picking an index, the order of tables in the ** join might be different so we have to recompute the usable flag ** each time. */ pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint; pUsage = pIdxInfo->aConstraintUsage; for(i=0; i<pIdxInfo->nConstraint; i++, pIdxCons++){ j = pIdxCons->iTermOffset; pTerm = &pWC->a[j]; pIdxCons->usable = (pTerm->prereqRight¬Ready) ? 0 : 1; } memset(pUsage, 0, sizeof(pUsage[0])*pIdxInfo->nConstraint); if( pIdxInfo->needToFreeIdxStr ){ sqlite3_free(pIdxInfo->idxStr); } pIdxInfo->idxStr = 0; pIdxInfo->idxNum = 0; pIdxInfo->needToFreeIdxStr = 0; pIdxInfo->orderByConsumed = 0; /* ((double)2) In case of SQLITE_OMIT_FLOATING_POINT... */ pIdxInfo->estimatedCost = SQLITE_BIG_DBL / ((double)2); nOrderBy = pIdxInfo->nOrderBy; if( !pOrderBy ){ pIdxInfo->nOrderBy = 0; } if( vtabBestIndex(pParse, pTab, pIdxInfo) ){ return; } pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint; for(i=0; i<pIdxInfo->nConstraint; i++){ if( pUsage[i].argvIndex>0 ){ pCost->used |= pWC->a[pIdxCons[i].iTermOffset].prereqRight; } } /* If there is an ORDER BY clause, and the selected virtual table index ** does not satisfy it, increase the cost of the scan accordingly. This ** matches the processing for non-virtual tables in bestBtreeIndex(). */ rCost = pIdxInfo->estimatedCost; if( pOrderBy && pIdxInfo->orderByConsumed==0 ){ rCost += estLog(rCost)*rCost; } /* The cost is not allowed to be larger than SQLITE_BIG_DBL (the ** inital value of lowestCost in this loop. If it is, then the ** (cost<lowestCost) test below will never be true. ** ** Use "(double)2" instead of "2.0" in case OMIT_FLOATING_POINT ** is defined. */ if( (SQLITE_BIG_DBL/((double)2))<rCost ){ pCost->rCost = (SQLITE_BIG_DBL/((double)2)); }else{ pCost->rCost = rCost; } pCost->plan.u.pVtabIdx = pIdxInfo; if( pIdxInfo->orderByConsumed ){ pCost->plan.wsFlags |= WHERE_ORDERBY; } pCost->plan.nEq = 0; pIdxInfo->nOrderBy = nOrderBy; /* Try to find a more efficient access pattern by using multiple indexes ** to optimize an OR expression within the WHERE clause. */ bestOrClauseIndex(pParse, pWC, pSrc, notReady, notValid, pOrderBy, pCost); } #endif /* SQLITE_OMIT_VIRTUALTABLE */ /* ** Argument pIdx is a pointer to an index structure that has an array of ** SQLITE_INDEX_SAMPLES evenly spaced samples of the first indexed column ** stored in Index.aSample. These samples divide the domain of values stored ** the index into (SQLITE_INDEX_SAMPLES+1) regions. ** Region 0 contains all values less than the first sample value. Region ** 1 contains values between the first and second samples. Region 2 contains ** values between samples 2 and 3. And so on. Region SQLITE_INDEX_SAMPLES ** contains values larger than the last sample. ** ** If the index contains many duplicates of a single value, then it is ** possible that two or more adjacent samples can hold the same value. ** When that is the case, the smallest possible region code is returned ** when roundUp is false and the largest possible region code is returned ** when roundUp is true. ** ** If successful, this function determines which of the regions value ** pVal lies in, sets *piRegion to the region index (a value between 0 ** and SQLITE_INDEX_SAMPLES+1, inclusive) and returns SQLITE_OK. ** Or, if an OOM occurs while converting text values between encodings, ** SQLITE_NOMEM is returned and *piRegion is undefined. */ #ifdef SQLITE_ENABLE_STAT2 static int whereRangeRegion( Parse *pParse, /* Database connection */ Index *pIdx, /* Index to consider domain of */ sqlite3_value *pVal, /* Value to consider */ int roundUp, /* Return largest valid region if true */ int *piRegion /* OUT: Region of domain in which value lies */ ){ assert( roundUp==0 || roundUp==1 ); if( ALWAYS(pVal) ){ IndexSample *aSample = pIdx->aSample; int i = 0; int eType = sqlite3_value_type(pVal); if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){ double r = sqlite3_value_double(pVal); for(i=0; i<SQLITE_INDEX_SAMPLES; i++){ if( aSample[i].eType==SQLITE_NULL ) continue; if( aSample[i].eType>=SQLITE_TEXT ) break; if( roundUp ){ if( aSample[i].u.r>r ) break; }else{ if( aSample[i].u.r>=r ) break; } } }else if( eType==SQLITE_NULL ){ i = 0; if( roundUp ){ while( i<SQLITE_INDEX_SAMPLES && aSample[i].eType==SQLITE_NULL ) i++; } }else{ sqlite3 *db = pParse->db; CollSeq *pColl; const u8 *z; int n; /* pVal comes from sqlite3ValueFromExpr() so the type cannot be NULL */ assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB ); if( eType==SQLITE_BLOB ){ z = (const u8 *)sqlite3_value_blob(pVal); pColl = db->pDfltColl; assert( pColl->enc==SQLITE_UTF8 ); }else{ pColl = sqlite3GetCollSeq(db, SQLITE_UTF8, 0, *pIdx->azColl); if( pColl==0 ){ sqlite3ErrorMsg(pParse, "no such collation sequence: %s", *pIdx->azColl); return SQLITE_ERROR; } z = (const u8 *)sqlite3ValueText(pVal, pColl->enc); if( !z ){ return SQLITE_NOMEM; } assert( z && pColl && pColl->xCmp ); } n = sqlite3ValueBytes(pVal, pColl->enc); for(i=0; i<SQLITE_INDEX_SAMPLES; i++){ int c; int eSampletype = aSample[i].eType; if( eSampletype==SQLITE_NULL || eSampletype<eType ) continue; if( (eSampletype!=eType) ) break; #ifndef SQLITE_OMIT_UTF16 if( pColl->enc!=SQLITE_UTF8 ){ int nSample; char *zSample = sqlite3Utf8to16( db, pColl->enc, aSample[i].u.z, aSample[i].nByte, &nSample ); if( !zSample ){ assert( db->mallocFailed ); return SQLITE_NOMEM; } c = pColl->xCmp(pColl->pUser, nSample, zSample, n, z); sqlite3DbFree(db, zSample); }else #endif { c = pColl->xCmp(pColl->pUser, aSample[i].nByte, aSample[i].u.z, n, z); } if( c-roundUp>=0 ) break; } } assert( i>=0 && i<=SQLITE_INDEX_SAMPLES ); *piRegion = i; } return SQLITE_OK; } #endif /* #ifdef SQLITE_ENABLE_STAT2 */ /* ** If expression pExpr represents a literal value, set *pp to point to ** an sqlite3_value structure containing the same value, with affinity ** aff applied to it, before returning. It is the responsibility of the ** caller to eventually release this structure by passing it to ** sqlite3ValueFree(). ** ** If the current parse is a recompile (sqlite3Reprepare()) and pExpr ** is an SQL variable that currently has a non-NULL value bound to it, ** create an sqlite3_value structure containing this value, again with ** affinity aff applied to it, instead. ** ** If neither of the above apply, set *pp to NULL. ** ** If an error occurs, return an error code. Otherwise, SQLITE_OK. */ #ifdef SQLITE_ENABLE_STAT2 static int valueFromExpr( Parse *pParse, Expr *pExpr, u8 aff, sqlite3_value **pp ){ if( pExpr->op==TK_VARIABLE || (pExpr->op==TK_REGISTER && pExpr->op2==TK_VARIABLE) ){ int iVar = pExpr->iColumn; sqlite3VdbeSetVarmask(pParse->pVdbe, iVar); /* IMP: R-23257-02778 */ *pp = sqlite3VdbeGetValue(pParse->pReprepare, iVar, aff); return SQLITE_OK; } return sqlite3ValueFromExpr(pParse->db, pExpr, SQLITE_UTF8, aff, pp); } #endif /* ** This function is used to estimate the number of rows that will be visited ** by scanning an index for a range of values. The range may have an upper ** bound, a lower bound, or both. The WHERE clause terms that set the upper ** and lower bounds are represented by pLower and pUpper respectively. For ** example, assuming that index p is on t1(a): ** ** ... FROM t1 WHERE a > ? AND a < ? ... ** |_____| |_____| ** | | ** pLower pUpper ** ** If either of the upper or lower bound is not present, then NULL is passed in ** place of the corresponding WhereTerm. ** ** The nEq parameter is passed the index of the index column subject to the ** range constraint. Or, equivalently, the number of equality constraints ** optimized by the proposed index scan. For example, assuming index p is ** on t1(a, b), and the SQL query is: ** ** ... FROM t1 WHERE a = ? AND b > ? AND b < ? ... ** ** then nEq should be passed the value 1 (as the range restricted column, ** b, is the second left-most column of the index). Or, if the query is: ** ** ... FROM t1 WHERE a > ? AND a < ? ... ** ** then nEq should be passed 0. ** ** The returned value is an integer between 1 and 100, inclusive. A return ** value of 1 indicates that the proposed range scan is expected to visit ** approximately 1/100th (1%) of the rows selected by the nEq equality ** constraints (if any). A return value of 100 indicates that it is expected ** that the range scan will visit every row (100%) selected by the equality ** constraints. ** ** In the absence of sqlite_stat2 ANALYZE data, each range inequality ** reduces the search space by 3/4ths. Hence a single constraint (x>?) ** results in a return of 25 and a range constraint (x>? AND x<?) results ** in a return of 6. */ static int whereRangeScanEst( Parse *pParse, /* Parsing & code generating context */ Index *p, /* The index containing the range-compared column; "x" */ int nEq, /* index into p->aCol[] of the range-compared column */ WhereTerm *pLower, /* Lower bound on the range. ex: "x>123" Might be NULL */ WhereTerm *pUpper, /* Upper bound on the range. ex: "x<455" Might be NULL */ int *piEst /* OUT: Return value */ ){ int rc = SQLITE_OK; #ifdef SQLITE_ENABLE_STAT2 if( nEq==0 && p->aSample ){ sqlite3_value *pLowerVal = 0; sqlite3_value *pUpperVal = 0; int iEst; int iLower = 0; int iUpper = SQLITE_INDEX_SAMPLES; int roundUpUpper = 0; int roundUpLower = 0; u8 aff = p->pTable->aCol[p->aiColumn[0]].affinity; if( pLower ){ Expr *pExpr = pLower->pExpr->pRight; rc = valueFromExpr(pParse, pExpr, aff, &pLowerVal); assert( pLower->eOperator==WO_GT || pLower->eOperator==WO_GE ); roundUpLower = (pLower->eOperator==WO_GT) ?1:0; } if( rc==SQLITE_OK && pUpper ){ Expr *pExpr = pUpper->pExpr->pRight; rc = valueFromExpr(pParse, pExpr, aff, &pUpperVal); assert( pUpper->eOperator==WO_LT || pUpper->eOperator==WO_LE ); roundUpUpper = (pUpper->eOperator==WO_LE) ?1:0; } if( rc!=SQLITE_OK || (pLowerVal==0 && pUpperVal==0) ){ sqlite3ValueFree(pLowerVal); sqlite3ValueFree(pUpperVal); goto range_est_fallback; }else if( pLowerVal==0 ){ rc = whereRangeRegion(pParse, p, pUpperVal, roundUpUpper, &iUpper); if( pLower ) iLower = iUpper/2; }else if( pUpperVal==0 ){ rc = whereRangeRegion(pParse, p, pLowerVal, roundUpLower, &iLower); if( pUpper ) iUpper = (iLower + SQLITE_INDEX_SAMPLES + 1)/2; }else{ rc = whereRangeRegion(pParse, p, pUpperVal, roundUpUpper, &iUpper); if( rc==SQLITE_OK ){ rc = whereRangeRegion(pParse, p, pLowerVal, roundUpLower, &iLower); } } WHERETRACE(("range scan regions: %d..%d\n", iLower, iUpper)); iEst = iUpper - iLower; testcase( iEst==SQLITE_INDEX_SAMPLES ); assert( iEst<=SQLITE_INDEX_SAMPLES ); if( iEst<1 ){ *piEst = 50/SQLITE_INDEX_SAMPLES; }else{ *piEst = (iEst*100)/SQLITE_INDEX_SAMPLES; } sqlite3ValueFree(pLowerVal); sqlite3ValueFree(pUpperVal); return rc; } range_est_fallback: #else UNUSED_PARAMETER(pParse); UNUSED_PARAMETER(p); UNUSED_PARAMETER(nEq); #endif assert( pLower || pUpper ); *piEst = 100; if( pLower && (pLower->wtFlags & TERM_VNULL)==0 ) *piEst /= 4; if( pUpper ) *piEst /= 4; return rc; } #ifdef SQLITE_ENABLE_STAT2 /* ** Estimate the number of rows that will be returned based on ** an equality constraint x=VALUE and where that VALUE occurs in ** the histogram data. This only works when x is the left-most ** column of an index and sqlite_stat2 histogram data is available ** for that index. When pExpr==NULL that means the constraint is ** "x IS NULL" instead of "x=VALUE". ** ** Write the estimated row count into *pnRow and return SQLITE_OK. ** If unable to make an estimate, leave *pnRow unchanged and return ** non-zero. ** ** This routine can fail if it is unable to load a collating sequence ** required for string comparison, or if unable to allocate memory ** for a UTF conversion required for comparison. The error is stored ** in the pParse structure. */ static int whereEqualScanEst( Parse *pParse, /* Parsing & code generating context */ Index *p, /* The index whose left-most column is pTerm */ Expr *pExpr, /* Expression for VALUE in the x=VALUE constraint */ double *pnRow /* Write the revised row estimate here */ ){ sqlite3_value *pRhs = 0; /* VALUE on right-hand side of pTerm */ int iLower, iUpper; /* Range of histogram regions containing pRhs */ u8 aff; /* Column affinity */ int rc; /* Subfunction return code */ double nRowEst; /* New estimate of the number of rows */ assert( p->aSample!=0 ); aff = p->pTable->aCol[p->aiColumn[0]].affinity; if( pExpr ){ rc = valueFromExpr(pParse, pExpr, aff, &pRhs); if( rc ) goto whereEqualScanEst_cancel; }else{ pRhs = sqlite3ValueNew(pParse->db); } if( pRhs==0 ) return SQLITE_NOTFOUND; rc = whereRangeRegion(pParse, p, pRhs, 0, &iLower); if( rc ) goto whereEqualScanEst_cancel; rc = whereRangeRegion(pParse, p, pRhs, 1, &iUpper); if( rc ) goto whereEqualScanEst_cancel; WHERETRACE(("equality scan regions: %d..%d\n", iLower, iUpper)); if( iLower>=iUpper ){ nRowEst = p->aiRowEst[0]/(SQLITE_INDEX_SAMPLES*2); if( nRowEst<*pnRow ) *pnRow = nRowEst; }else{ nRowEst = (iUpper-iLower)*p->aiRowEst[0]/SQLITE_INDEX_SAMPLES; *pnRow = nRowEst; } whereEqualScanEst_cancel: sqlite3ValueFree(pRhs); return rc; } #endif /* defined(SQLITE_ENABLE_STAT2) */ #ifdef SQLITE_ENABLE_STAT2 /* ** Estimate the number of rows that will be returned based on ** an IN constraint where the right-hand side of the IN operator ** is a list of values. Example: ** ** WHERE x IN (1,2,3,4) ** ** Write the estimated row count into *pnRow and return SQLITE_OK. ** If unable to make an estimate, leave *pnRow unchanged and return ** non-zero. ** ** This routine can fail if it is unable to load a collating sequence ** required for string comparison, or if unable to allocate memory ** for a UTF conversion required for comparison. The error is stored ** in the pParse structure. */ static int whereInScanEst( Parse *pParse, /* Parsing & code generating context */ Index *p, /* The index whose left-most column is pTerm */ ExprList *pList, /* The value list on the RHS of "x IN (v1,v2,v3,...)" */ double *pnRow /* Write the revised row estimate here */ ){ sqlite3_value *pVal = 0; /* One value from list */ int iLower, iUpper; /* Range of histogram regions containing pRhs */ u8 aff; /* Column affinity */ int rc = SQLITE_OK; /* Subfunction return code */ double nRowEst; /* New estimate of the number of rows */ int nSpan = 0; /* Number of histogram regions spanned */ int nSingle = 0; /* Histogram regions hit by a single value */ int nNotFound = 0; /* Count of values that are not constants */ int i; /* Loop counter */ u8 aSpan[SQLITE_INDEX_SAMPLES+1]; /* Histogram regions that are spanned */ u8 aSingle[SQLITE_INDEX_SAMPLES+1]; /* Histogram regions hit once */ assert( p->aSample!=0 ); aff = p->pTable->aCol[p->aiColumn[0]].affinity; memset(aSpan, 0, sizeof(aSpan)); memset(aSingle, 0, sizeof(aSingle)); for(i=0; i<pList->nExpr; i++){ sqlite3ValueFree(pVal); rc = valueFromExpr(pParse, pList->a[i].pExpr, aff, &pVal); if( rc ) break; if( pVal==0 || sqlite3_value_type(pVal)==SQLITE_NULL ){ nNotFound++; continue; } rc = whereRangeRegion(pParse, p, pVal, 0, &iLower); if( rc ) break; rc = whereRangeRegion(pParse, p, pVal, 1, &iUpper); if( rc ) break; if( iLower>=iUpper ){ aSingle[iLower] = 1; }else{ assert( iLower>=0 && iUpper<=SQLITE_INDEX_SAMPLES ); while( iLower<iUpper ) aSpan[iLower++] = 1; } } if( rc==SQLITE_OK ){ for(i=nSpan=0; i<=SQLITE_INDEX_SAMPLES; i++){ if( aSpan[i] ){ nSpan++; }else if( aSingle[i] ){ nSingle++; } } nRowEst = (nSpan*2+nSingle)*p->aiRowEst[0]/(2*SQLITE_INDEX_SAMPLES) + nNotFound*p->aiRowEst[1]; if( nRowEst > p->aiRowEst[0] ) nRowEst = p->aiRowEst[0]; *pnRow = nRowEst; WHERETRACE(("IN row estimate: nSpan=%d, nSingle=%d, nNotFound=%d, est=%g\n", nSpan, nSingle, nNotFound, nRowEst)); } sqlite3ValueFree(pVal); return rc; } #endif /* defined(SQLITE_ENABLE_STAT2) */ /* ** Find the best query plan for accessing a particular table. Write the ** best query plan and its cost into the WhereCost object supplied as the ** last parameter. ** ** The lowest cost plan wins. The cost is an estimate of the amount of ** CPU and disk I/O needed to process the requested result. ** Factors that influence cost include: ** ** * The estimated number of rows that will be retrieved. (The ** fewer the better.) ** ** * Whether or not sorting must occur. ** ** * Whether or not there must be separate lookups in the ** index and in the main table. ** ** If there was an INDEXED BY clause (pSrc->pIndex) attached to the table in ** the SQL statement, then this function only considers plans using the ** named index. If no such plan is found, then the returned cost is ** SQLITE_BIG_DBL. If a plan is found that uses the named index, ** then the cost is calculated in the usual way. ** ** If a NOT INDEXED clause (pSrc->notIndexed!=0) was attached to the table ** in the SELECT statement, then no indexes are considered. However, the ** selected plan may still take advantage of the built-in rowid primary key ** index. */ static void bestBtreeIndex( Parse *pParse, /* The parsing context */ WhereClause *pWC, /* The WHERE clause */ struct SrcList_item *pSrc, /* The FROM clause term to search */ Bitmask notReady, /* Mask of cursors not available for indexing */ Bitmask notValid, /* Cursors not available for any purpose */ ExprList *pOrderBy, /* The ORDER BY clause */ WhereCost *pCost /* Lowest cost query plan */ ){ int iCur = pSrc->iCursor; /* The cursor of the table to be accessed */ Index *pProbe; /* An index we are evaluating */ Index *pIdx; /* Copy of pProbe, or zero for IPK index */ int eqTermMask; /* Current mask of valid equality operators */ int idxEqTermMask; /* Index mask of valid equality operators */ Index sPk; /* A fake index object for the primary key */ unsigned int aiRowEstPk[2]; /* The aiRowEst[] value for the sPk index */ int aiColumnPk = -1; /* The aColumn[] value for the sPk index */ int wsFlagMask; /* Allowed flags in pCost->plan.wsFlag */ /* Initialize the cost to a worst-case value */ memset(pCost, 0, sizeof(*pCost)); pCost->rCost = SQLITE_BIG_DBL; /* If the pSrc table is the right table of a LEFT JOIN then we may not ** use an index to satisfy IS NULL constraints on that table. This is ** because columns might end up being NULL if the table does not match - ** a circumstance which the index cannot help us discover. Ticket #2177. */ if( pSrc->jointype & JT_LEFT ){ idxEqTermMask = WO_EQ|WO_IN; }else{ idxEqTermMask = WO_EQ|WO_IN|WO_ISNULL; } if( pSrc->pIndex ){ /* An INDEXED BY clause specifies a particular index to use */ pIdx = pProbe = pSrc->pIndex; wsFlagMask = ~(WHERE_ROWID_EQ|WHERE_ROWID_RANGE); eqTermMask = idxEqTermMask; }else{ /* There is no INDEXED BY clause. Create a fake Index object in local ** variable sPk to represent the rowid primary key index. Make this ** fake index the first in a chain of Index objects with all of the real ** indices to follow */ Index *pFirst; /* First of real indices on the table */ memset(&sPk, 0, sizeof(Index)); sPk.nColumn = 1; sPk.aiColumn = &aiColumnPk; sPk.aiRowEst = aiRowEstPk; sPk.onError = OE_Replace; sPk.pTable = pSrc->pTab; aiRowEstPk[0] = pSrc->pTab->nRowEst; aiRowEstPk[1] = 1; pFirst = pSrc->pTab->pIndex; if( pSrc->notIndexed==0 ){ /* The real indices of the table are only considered if the ** NOT INDEXED qualifier is omitted from the FROM clause */ sPk.pNext = pFirst; } pProbe = &sPk; wsFlagMask = ~( WHERE_COLUMN_IN|WHERE_COLUMN_EQ|WHERE_COLUMN_NULL|WHERE_COLUMN_RANGE ); eqTermMask = WO_EQ|WO_IN; pIdx = 0; } /* Loop over all indices looking for the best one to use */ for(; pProbe; pIdx=pProbe=pProbe->pNext){ const unsigned int * const aiRowEst = pProbe->aiRowEst; double cost; /* Cost of using pProbe */ double nRow; /* Estimated number of rows in result set */ double log10N; /* base-10 logarithm of nRow (inexact) */ int rev; /* True to scan in reverse order */ int wsFlags = 0; Bitmask used = 0; /* The following variables are populated based on the properties of ** index being evaluated. They are then used to determine the expected ** cost and number of rows returned. ** ** nEq: ** Number of equality terms that can be implemented using the index. ** In other words, the number of initial fields in the index that ** are used in == or IN or NOT NULL constraints of the WHERE clause. ** ** nInMul: ** The "in-multiplier". This is an estimate of how many seek operations ** SQLite must perform on the index in question. For example, if the ** WHERE clause is: ** ** WHERE a IN (1, 2, 3) AND b IN (4, 5, 6) ** ** SQLite must perform 9 lookups on an index on (a, b), so nInMul is ** set to 9. Given the same schema and either of the following WHERE ** clauses: ** ** WHERE a = 1 ** WHERE a >= 2 ** ** nInMul is set to 1. ** ** If there exists a WHERE term of the form "x IN (SELECT ...)", then ** the sub-select is assumed to return 25 rows for the purposes of ** determining nInMul. ** ** bInEst: ** Set to true if there was at least one "x IN (SELECT ...)" term used ** in determining the value of nInMul. Note that the RHS of the ** IN operator must be a SELECT, not a value list, for this variable ** to be true. ** ** estBound: ** An estimate on the amount of the table that must be searched. A ** value of 100 means the entire table is searched. Range constraints ** might reduce this to a value less than 100 to indicate that only ** a fraction of the table needs searching. In the absence of ** sqlite_stat2 ANALYZE data, a single inequality reduces the search ** space to 1/4rd its original size. So an x>? constraint reduces ** estBound to 25. Two constraints (x>? AND x<?) reduce estBound to 6. ** ** bSort: ** Boolean. True if there is an ORDER BY clause that will require an ** external sort (i.e. scanning the index being evaluated will not ** correctly order records). ** ** bLookup: ** Boolean. True if a table lookup is required for each index entry ** visited. In other words, true if this is not a covering index. ** This is always false for the rowid primary key index of a table. ** For other indexes, it is true unless all the columns of the table ** used by the SELECT statement are present in the index (such an ** index is sometimes described as a covering index). ** For example, given the index on (a, b), the second of the following ** two queries requires table b-tree lookups in order to find the value ** of column c, but the first does not because columns a and b are ** both available in the index. ** ** SELECT a, b FROM tbl WHERE a = 1; ** SELECT a, b, c FROM tbl WHERE a = 1; */ int nEq; /* Number of == or IN terms matching index */ int bInEst = 0; /* True if "x IN (SELECT...)" seen */ int nInMul = 1; /* Number of distinct equalities to lookup */ int estBound = 100; /* Estimated reduction in search space */ int nBound = 0; /* Number of range constraints seen */ int bSort = 0; /* True if external sort required */ int bLookup = 0; /* True if not a covering index */ WhereTerm *pTerm; /* A single term of the WHERE clause */ #ifdef SQLITE_ENABLE_STAT2 WhereTerm *pFirstTerm = 0; /* First term matching the index */ #endif /* Determine the values of nEq and nInMul */ for(nEq=0; nEq<pProbe->nColumn; nEq++){ int j = pProbe->aiColumn[nEq]; pTerm = findTerm(pWC, iCur, j, notReady, eqTermMask, pIdx); if( pTerm==0 ) break; wsFlags |= (WHERE_COLUMN_EQ|WHERE_ROWID_EQ); if( pTerm->eOperator & WO_IN ){ Expr *pExpr = pTerm->pExpr; wsFlags |= WHERE_COLUMN_IN; if( ExprHasProperty(pExpr, EP_xIsSelect) ){ /* "x IN (SELECT ...)": Assume the SELECT returns 25 rows */ nInMul *= 25; bInEst = 1; }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){ /* "x IN (value, value, ...)" */ nInMul *= pExpr->x.pList->nExpr; } }else if( pTerm->eOperator & WO_ISNULL ){ wsFlags |= WHERE_COLUMN_NULL; } #ifdef SQLITE_ENABLE_STAT2 if( nEq==0 && pProbe->aSample ) pFirstTerm = pTerm; #endif used |= pTerm->prereqRight; } /* Determine the value of estBound. */ if( nEq<pProbe->nColumn && pProbe->bUnordered==0 ){ int j = pProbe->aiColumn[nEq]; if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pIdx) ){ WhereTerm *pTop = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pIdx); WhereTerm *pBtm = findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pIdx); whereRangeScanEst(pParse, pProbe, nEq, pBtm, pTop, &estBound); if( pTop ){ nBound = 1; wsFlags |= WHERE_TOP_LIMIT; used |= pTop->prereqRight; } if( pBtm ){ nBound++; wsFlags |= WHERE_BTM_LIMIT; used |= pBtm->prereqRight; } wsFlags |= (WHERE_COLUMN_RANGE|WHERE_ROWID_RANGE); } }else if( pProbe->onError!=OE_None ){ testcase( wsFlags & WHERE_COLUMN_IN ); testcase( wsFlags & WHERE_COLUMN_NULL ); if( (wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_NULL))==0 ){ wsFlags |= WHERE_UNIQUE; } } /* If there is an ORDER BY clause and the index being considered will ** naturally scan rows in the required order, set the appropriate flags ** in wsFlags. Otherwise, if there is an ORDER BY clause but the index ** will scan rows in a different order, set the bSort variable. */ if( pOrderBy ){ if( (wsFlags & WHERE_COLUMN_IN)==0 && pProbe->bUnordered==0 && isSortingIndex(pParse, pWC->pMaskSet, pProbe, iCur, pOrderBy, nEq, wsFlags, &rev) ){ wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_ORDERBY; wsFlags |= (rev ? WHERE_REVERSE : 0); }else{ bSort = 1; } } /* If currently calculating the cost of using an index (not the IPK ** index), determine if all required column data may be obtained without ** using the main table (i.e. if the index is a covering ** index for this query). If it is, set the WHERE_IDX_ONLY flag in ** wsFlags. Otherwise, set the bLookup variable to true. */ if( pIdx && wsFlags ){ Bitmask m = pSrc->colUsed; int j; for(j=0; j<pIdx->nColumn; j++){ int x = pIdx->aiColumn[j]; if( x<BMS-1 ){ m &= ~(((Bitmask)1)<<x); } } if( m==0 ){ wsFlags |= WHERE_IDX_ONLY; }else{ bLookup = 1; } } /* ** Estimate the number of rows of output. For an "x IN (SELECT...)" ** constraint, do not let the estimate exceed half the rows in the table. */ nRow = (double)(aiRowEst[nEq] * nInMul); if( bInEst && nRow*2>aiRowEst[0] ){ nRow = aiRowEst[0]/2; nInMul = (int)(nRow / aiRowEst[nEq]); } #ifdef SQLITE_ENABLE_STAT2 /* If the constraint is of the form x=VALUE and histogram ** data is available for column x, then it might be possible ** to get a better estimate on the number of rows based on ** VALUE and how common that value is according to the histogram. */ if( nRow>(double)1 && nEq==1 && pFirstTerm!=0 ){ if( pFirstTerm->eOperator & (WO_EQ|WO_ISNULL) ){ testcase( pFirstTerm->eOperator==WO_EQ ); testcase( pFirstTerm->eOperator==WO_ISNULL ); whereEqualScanEst(pParse, pProbe, pFirstTerm->pExpr->pRight, &nRow); }else if( pFirstTerm->eOperator==WO_IN && bInEst==0 ){ whereInScanEst(pParse, pProbe, pFirstTerm->pExpr->x.pList, &nRow); } } #endif /* SQLITE_ENABLE_STAT2 */ /* Adjust the number of output rows and downward to reflect rows ** that are excluded by range constraints. */ nRow = (nRow * (double)estBound) / (double)100; if( nRow<1 ) nRow = 1; /* Experiments run on real SQLite databases show that the time needed ** to do a binary search to locate a row in a table or index is roughly ** log10(N) times the time to move from one row to the next row within ** a table or index. The actual times can vary, with the size of ** records being an important factor. Both moves and searches are ** slower with larger records, presumably because fewer records fit ** on one page and hence more pages have to be fetched. ** ** The ANALYZE command and the sqlite_stat1 and sqlite_stat2 tables do ** not give us data on the relative sizes of table and index records. ** So this computation assumes table records are about twice as big ** as index records */ if( (wsFlags & WHERE_NOT_FULLSCAN)==0 ){ /* The cost of a full table scan is a number of move operations equal ** to the number of rows in the table. ** ** We add an additional 4x penalty to full table scans. This causes ** the cost function to err on the side of choosing an index over ** choosing a full scan. This 4x full-scan penalty is an arguable ** decision and one which we expect to revisit in the future. But ** it seems to be working well enough at the moment. */ cost = aiRowEst[0]*4; }else{ log10N = estLog(aiRowEst[0]); cost = nRow; if( pIdx ){ if( bLookup ){ /* For an index lookup followed by a table lookup: ** nInMul index searches to find the start of each index range ** + nRow steps through the index ** + nRow table searches to lookup the table entry using the rowid */ cost += (nInMul + nRow)*log10N; }else{ /* For a covering index: ** nInMul index searches to find the initial entry ** + nRow steps through the index */ cost += nInMul*log10N; } }else{ /* For a rowid primary key lookup: ** nInMult table searches to find the initial entry for each range ** + nRow steps through the table */ cost += nInMul*log10N; } } /* Add in the estimated cost of sorting the result. Actual experimental ** measurements of sorting performance in SQLite show that sorting time ** adds C*N*log10(N) to the cost, where N is the number of rows to be ** sorted and C is a factor between 1.95 and 4.3. We will split the ** difference and select C of 3.0. */ if( bSort ){ cost += nRow*estLog(nRow)*3; } /**** Cost of using this index has now been computed ****/ /* If there are additional constraints on this table that cannot ** be used with the current index, but which might lower the number ** of output rows, adjust the nRow value accordingly. This only ** matters if the current index is the least costly, so do not bother ** with this step if we already know this index will not be chosen. ** Also, never reduce the output row count below 2 using this step. ** ** It is critical that the notValid mask be used here instead of ** the notReady mask. When computing an "optimal" index, the notReady ** mask will only have one bit set - the bit for the current table. ** The notValid mask, on the other hand, always has all bits set for ** tables that are not in outer loops. If notReady is used here instead ** of notValid, then a optimal index that depends on inner joins loops ** might be selected even when there exists an optimal index that has ** no such dependency. */ if( nRow>2 && cost<=pCost->rCost ){ int k; /* Loop counter */ int nSkipEq = nEq; /* Number of == constraints to skip */ int nSkipRange = nBound; /* Number of < constraints to skip */ Bitmask thisTab; /* Bitmap for pSrc */ thisTab = getMask(pWC->pMaskSet, iCur); for(pTerm=pWC->a, k=pWC->nTerm; nRow>2 && k; k--, pTerm++){ if( pTerm->wtFlags & TERM_VIRTUAL ) continue; if( (pTerm->prereqAll & notValid)!=thisTab ) continue; if( pTerm->eOperator & (WO_EQ|WO_IN|WO_ISNULL) ){ if( nSkipEq ){ /* Ignore the first nEq equality matches since the index ** has already accounted for these */ nSkipEq--; }else{ /* Assume each additional equality match reduces the result ** set size by a factor of 10 */ nRow /= 10; } }else if( pTerm->eOperator & (WO_LT|WO_LE|WO_GT|WO_GE) ){ if( nSkipRange ){ /* Ignore the first nSkipRange range constraints since the index ** has already accounted for these */ nSkipRange--; }else{ /* Assume each additional range constraint reduces the result ** set size by a factor of 3. Indexed range constraints reduce ** the search space by a larger factor: 4. We make indexed range ** more selective intentionally because of the subjective ** observation that indexed range constraints really are more ** selective in practice, on average. */ nRow /= 3; } }else if( pTerm->eOperator!=WO_NOOP ){ /* Any other expression lowers the output row count by half */ nRow /= 2; } } if( nRow<2 ) nRow = 2; } WHERETRACE(( "%s(%s): nEq=%d nInMul=%d estBound=%d bSort=%d bLookup=%d wsFlags=0x%x\n" " notReady=0x%llx log10N=%.1f nRow=%.1f cost=%.1f used=0x%llx\n", pSrc->pTab->zName, (pIdx ? pIdx->zName : "ipk"), nEq, nInMul, estBound, bSort, bLookup, wsFlags, notReady, log10N, nRow, cost, used )); /* If this index is the best we have seen so far, then record this ** index and its cost in the pCost structure. */ if( (!pIdx || wsFlags) && (cost<pCost->rCost || (cost<=pCost->rCost && nRow<pCost->plan.nRow)) ){ pCost->rCost = cost; pCost->used = used; pCost->plan.nRow = nRow; pCost->plan.wsFlags = (wsFlags&wsFlagMask); pCost->plan.nEq = nEq; pCost->plan.u.pIdx = pIdx; } /* If there was an INDEXED BY clause, then only that one index is ** considered. */ if( pSrc->pIndex ) break; /* Reset masks for the next index in the loop */ wsFlagMask = ~(WHERE_ROWID_EQ|WHERE_ROWID_RANGE); eqTermMask = idxEqTermMask; } /* If there is no ORDER BY clause and the SQLITE_ReverseOrder flag ** is set, then reverse the order that the index will be scanned ** in. This is used for application testing, to help find cases ** where application behaviour depends on the (undefined) order that ** SQLite outputs rows in in the absence of an ORDER BY clause. */ if( !pOrderBy && pParse->db->flags & SQLITE_ReverseOrder ){ pCost->plan.wsFlags |= WHERE_REVERSE; } assert( pOrderBy || (pCost->plan.wsFlags&WHERE_ORDERBY)==0 ); assert( pCost->plan.u.pIdx==0 || (pCost->plan.wsFlags&WHERE_ROWID_EQ)==0 ); assert( pSrc->pIndex==0 || pCost->plan.u.pIdx==0 || pCost->plan.u.pIdx==pSrc->pIndex ); WHERETRACE(("best index is: %s\n", ((pCost->plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ? "none" : pCost->plan.u.pIdx ? pCost->plan.u.pIdx->zName : "ipk") )); bestOrClauseIndex(pParse, pWC, pSrc, notReady, notValid, pOrderBy, pCost); bestAutomaticIndex(pParse, pWC, pSrc, notReady, pCost); pCost->plan.wsFlags |= eqTermMask; } /* ** Find the query plan for accessing table pSrc->pTab. Write the ** best query plan and its cost into the WhereCost object supplied ** as the last parameter. This function may calculate the cost of ** both real and virtual table scans. */ static void bestIndex( Parse *pParse, /* The parsing context */ WhereClause *pWC, /* The WHERE clause */ struct SrcList_item *pSrc, /* The FROM clause term to search */ Bitmask notReady, /* Mask of cursors not available for indexing */ Bitmask notValid, /* Cursors not available for any purpose */ ExprList *pOrderBy, /* The ORDER BY clause */ WhereCost *pCost /* Lowest cost query plan */ ){ #ifndef SQLITE_OMIT_VIRTUALTABLE if( IsVirtual(pSrc->pTab) ){ sqlite3_index_info *p = 0; bestVirtualIndex(pParse, pWC, pSrc, notReady, notValid, pOrderBy, pCost,&p); if( p->needToFreeIdxStr ){ sqlite3_free(p->idxStr); } sqlite3DbFree(pParse->db, p); }else #endif { bestBtreeIndex(pParse, pWC, pSrc, notReady, notValid, pOrderBy, pCost); } } /* ** Disable a term in the WHERE clause. Except, do not disable the term ** if it controls a LEFT OUTER JOIN and it did not originate in the ON ** or USING clause of that join. ** ** Consider the term t2.z='ok' in the following queries: ** ** (1) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x WHERE t2.z='ok' ** (2) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x AND t2.z='ok' ** (3) SELECT * FROM t1, t2 WHERE t1.a=t2.x AND t2.z='ok' ** ** The t2.z='ok' is disabled in the in (2) because it originates ** in the ON clause. The term is disabled in (3) because it is not part ** of a LEFT OUTER JOIN. In (1), the term is not disabled. ** ** IMPLEMENTATION-OF: R-24597-58655 No tests are done for terms that are ** completely satisfied by indices. ** ** Disabling a term causes that term to not be tested in the inner loop ** of the join. Disabling is an optimization. When terms are satisfied ** by indices, we disable them to prevent redundant tests in the inner ** loop. We would get the correct results if nothing were ever disabled, ** but joins might run a little slower. The trick is to disable as much ** as we can without disabling too much. If we disabled in (1), we'd get ** the wrong answer. See ticket #813. */ static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){ if( pTerm && (pTerm->wtFlags & TERM_CODED)==0 && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin)) ){ pTerm->wtFlags |= TERM_CODED; if( pTerm->iParent>=0 ){ WhereTerm *pOther = &pTerm->pWC->a[pTerm->iParent]; if( (--pOther->nChild)==0 ){ disableTerm(pLevel, pOther); } } } } /* ** Code an OP_Affinity opcode to apply the column affinity string zAff ** to the n registers starting at base. ** ** As an optimization, SQLITE_AFF_NONE entries (which are no-ops) at the ** beginning and end of zAff are ignored. If all entries in zAff are ** SQLITE_AFF_NONE, then no code gets generated. ** ** This routine makes its own copy of zAff so that the caller is free ** to modify zAff after this routine returns. */ static void codeApplyAffinity(Parse *pParse, int base, int n, char *zAff){ Vdbe *v = pParse->pVdbe; if( zAff==0 ){ assert( pParse->db->mallocFailed ); return; } assert( v!=0 ); /* Adjust base and n to skip over SQLITE_AFF_NONE entries at the beginning ** and end of the affinity string. */ while( n>0 && zAff[0]==SQLITE_AFF_NONE ){ n--; base++; zAff++; } while( n>1 && zAff[n-1]==SQLITE_AFF_NONE ){ n--; } /* Code the OP_Affinity opcode if there is anything left to do. */ if( n>0 ){ sqlite3VdbeAddOp2(v, OP_Affinity, base, n); sqlite3VdbeChangeP4(v, -1, zAff, n); sqlite3ExprCacheAffinityChange(pParse, base, n); } } /* ** Generate code for a single equality term of the WHERE clause. An equality ** term can be either X=expr or X IN (...). pTerm is the term to be ** coded. ** ** The current value for the constraint is left in register iReg. ** ** For a constraint of the form X=expr, the expression is evaluated and its ** result is left on the stack. For constraints of the form X IN (...) ** this routine sets up a loop that will iterate over all values of X. */ static int codeEqualityTerm( Parse *pParse, /* The parsing context */ WhereTerm *pTerm, /* The term of the WHERE clause to be coded */ WhereLevel *pLevel, /* When level of the FROM clause we are working on */ int iTarget /* Attempt to leave results in this register */ ){ Expr *pX = pTerm->pExpr; Vdbe *v = pParse->pVdbe; int iReg; /* Register holding results */ assert( iTarget>0 ); if( pX->op==TK_EQ ){ iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget); }else if( pX->op==TK_ISNULL ){ iReg = iTarget; sqlite3VdbeAddOp2(v, OP_Null, 0, iReg); #ifndef SQLITE_OMIT_SUBQUERY }else{ int eType; int iTab; struct InLoop *pIn; assert( pX->op==TK_IN ); iReg = iTarget; eType = sqlite3FindInIndex(pParse, pX, 0); iTab = pX->iTable; sqlite3VdbeAddOp2(v, OP_Rewind, iTab, 0); assert( pLevel->plan.wsFlags & WHERE_IN_ABLE ); if( pLevel->u.in.nIn==0 ){ pLevel->addrNxt = sqlite3VdbeMakeLabel(v); } pLevel->u.in.nIn++; pLevel->u.in.aInLoop = sqlite3DbReallocOrFree(pParse->db, pLevel->u.in.aInLoop, sizeof(pLevel->u.in.aInLoop[0])*pLevel->u.in.nIn); pIn = pLevel->u.in.aInLoop; if( pIn ){ pIn += pLevel->u.in.nIn - 1; pIn->iCur = iTab; if( eType==IN_INDEX_ROWID ){ pIn->addrInTop = sqlite3VdbeAddOp2(v, OP_Rowid, iTab, iReg); }else{ pIn->addrInTop = sqlite3VdbeAddOp3(v, OP_Column, iTab, 0, iReg); } sqlite3VdbeAddOp1(v, OP_IsNull, iReg); }else{ pLevel->u.in.nIn = 0; } #endif } disableTerm(pLevel, pTerm); return iReg; } /* ** Generate code that will evaluate all == and IN constraints for an ** index. ** ** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c). ** Suppose the WHERE clause is this: a==5 AND b IN (1,2,3) AND c>5 AND c<10 ** The index has as many as three equality constraints, but in this ** example, the third "c" value is an inequality. So only two ** constraints are coded. This routine will generate code to evaluate ** a==5 and b IN (1,2,3). The current values for a and b will be stored ** in consecutive registers and the index of the first register is returned. ** ** In the example above nEq==2. But this subroutine works for any value ** of nEq including 0. If nEq==0, this routine is nearly a no-op. ** The only thing it does is allocate the pLevel->iMem memory cell and ** compute the affinity string. ** ** This routine always allocates at least one memory cell and returns ** the index of that memory cell. The code that ** calls this routine will use that memory cell to store the termination ** key value of the loop. If one or more IN operators appear, then ** this routine allocates an additional nEq memory cells for internal ** use. ** ** Before returning, *pzAff is set to point to a buffer containing a ** copy of the column affinity string of the index allocated using ** sqlite3DbMalloc(). Except, entries in the copy of the string associated ** with equality constraints that use NONE affinity are set to ** SQLITE_AFF_NONE. This is to deal with SQL such as the following: ** ** CREATE TABLE t1(a TEXT PRIMARY KEY, b); ** SELECT ... FROM t1 AS t2, t1 WHERE t1.a = t2.b; ** ** In the example above, the index on t1(a) has TEXT affinity. But since ** the right hand side of the equality constraint (t2.b) has NONE affinity, ** no conversion should be attempted before using a t2.b value as part of ** a key to search the index. Hence the first byte in the returned affinity ** string in this example would be set to SQLITE_AFF_NONE. */ static int codeAllEqualityTerms( Parse *pParse, /* Parsing context */ WhereLevel *pLevel, /* Which nested loop of the FROM we are coding */ WhereClause *pWC, /* The WHERE clause */ Bitmask notReady, /* Which parts of FROM have not yet been coded */ int nExtraReg, /* Number of extra registers to allocate */ char **pzAff /* OUT: Set to point to affinity string */ ){ int nEq = pLevel->plan.nEq; /* The number of == or IN constraints to code */ Vdbe *v = pParse->pVdbe; /* The vm under construction */ Index *pIdx; /* The index being used for this loop */ int iCur = pLevel->iTabCur; /* The cursor of the table */ WhereTerm *pTerm; /* A single constraint term */ int j; /* Loop counter */ int regBase; /* Base register */ int nReg; /* Number of registers to allocate */ char *zAff; /* Affinity string to return */ /* This module is only called on query plans that use an index. */ assert( pLevel->plan.wsFlags & WHERE_INDEXED ); pIdx = pLevel->plan.u.pIdx; /* Figure out how many memory cells we will need then allocate them. */ regBase = pParse->nMem + 1; nReg = pLevel->plan.nEq + nExtraReg; pParse->nMem += nReg; zAff = sqlite3DbStrDup(pParse->db, sqlite3IndexAffinityStr(v, pIdx)); if( !zAff ){ pParse->db->mallocFailed = 1; } /* Evaluate the equality constraints */ assert( pIdx->nColumn>=nEq ); for(j=0; j<nEq; j++){ int r1; int k = pIdx->aiColumn[j]; pTerm = findTerm(pWC, iCur, k, notReady, pLevel->plan.wsFlags, pIdx); if( NEVER(pTerm==0) ) break; /* The following true for indices with redundant columns. ** Ex: CREATE INDEX i1 ON t1(a,b,a); SELECT * FROM t1 WHERE a=0 AND b=0; */ testcase( (pTerm->wtFlags & TERM_CODED)!=0 ); testcase( pTerm->wtFlags & TERM_VIRTUAL ); /* EV: R-30575-11662 */ r1 = codeEqualityTerm(pParse, pTerm, pLevel, regBase+j); if( r1!=regBase+j ){ if( nReg==1 ){ sqlite3ReleaseTempReg(pParse, regBase); regBase = r1; }else{ sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j); } } testcase( pTerm->eOperator & WO_ISNULL ); testcase( pTerm->eOperator & WO_IN ); if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){ Expr *pRight = pTerm->pExpr->pRight; sqlite3ExprCodeIsNullJump(v, pRight, regBase+j, pLevel->addrBrk); if( zAff ){ if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_NONE ){ zAff[j] = SQLITE_AFF_NONE; } if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[j]) ){ zAff[j] = SQLITE_AFF_NONE; } } } } *pzAff = zAff; return regBase; } #ifndef SQLITE_OMIT_EXPLAIN /* ** This routine is a helper for explainIndexRange() below ** ** pStr holds the text of an expression that we are building up one term ** at a time. This routine adds a new term to the end of the expression. ** Terms are separated by AND so add the "AND" text for second and subsequent ** terms only. */ static void explainAppendTerm( StrAccum *pStr, /* The text expression being built */ int iTerm, /* Index of this term. First is zero */ const char *zColumn, /* Name of the column */ const char *zOp /* Name of the operator */ ){ if( iTerm ) sqlite3StrAccumAppend(pStr, " AND ", 5); sqlite3StrAccumAppend(pStr, zColumn, -1); sqlite3StrAccumAppend(pStr, zOp, 1); sqlite3StrAccumAppend(pStr, "?", 1); } /* ** Argument pLevel describes a strategy for scanning table pTab. This ** function returns a pointer to a string buffer containing a description ** of the subset of table rows scanned by the strategy in the form of an ** SQL expression. Or, if all rows are scanned, NULL is returned. ** ** For example, if the query: ** ** SELECT * FROM t1 WHERE a=1 AND b>2; ** ** is run and there is an index on (a, b), then this function returns a ** string similar to: ** ** "a=? AND b>?" ** ** The returned pointer points to memory obtained from sqlite3DbMalloc(). ** It is the responsibility of the caller to free the buffer when it is ** no longer required. */ static char *explainIndexRange(sqlite3 *db, WhereLevel *pLevel, Table *pTab){ WherePlan *pPlan = &pLevel->plan; Index *pIndex = pPlan->u.pIdx; int nEq = pPlan->nEq; int i, j; Column *aCol = pTab->aCol; int *aiColumn = pIndex->aiColumn; StrAccum txt; if( nEq==0 && (pPlan->wsFlags & (WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))==0 ){ return 0; } sqlite3StrAccumInit(&txt, 0, 0, SQLITE_MAX_LENGTH); txt.db = db; sqlite3StrAccumAppend(&txt, " (", 2); for(i=0; i<nEq; i++){ explainAppendTerm(&txt, i, aCol[aiColumn[i]].zName, "="); } j = i; if( pPlan->wsFlags&WHERE_BTM_LIMIT ){ explainAppendTerm(&txt, i++, aCol[aiColumn[j]].zName, ">"); } if( pPlan->wsFlags&WHERE_TOP_LIMIT ){ explainAppendTerm(&txt, i, aCol[aiColumn[j]].zName, "<"); } sqlite3StrAccumAppend(&txt, ")", 1); return sqlite3StrAccumFinish(&txt); } /* ** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN ** command. If the query being compiled is an EXPLAIN QUERY PLAN, a single ** record is added to the output to describe the table scan strategy in ** pLevel. */ static void explainOneScan( Parse *pParse, /* Parse context */ SrcList *pTabList, /* Table list this loop refers to */ WhereLevel *pLevel, /* Scan to write OP_Explain opcode for */ int iLevel, /* Value for "level" column of output */ int iFrom, /* Value for "from" column of output */ u16 wctrlFlags /* Flags passed to sqlite3WhereBegin() */ ){ if( pParse->explain==2 ){ u32 flags = pLevel->plan.wsFlags; struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom]; Vdbe *v = pParse->pVdbe; /* VM being constructed */ sqlite3 *db = pParse->db; /* Database handle */ char *zMsg; /* Text to add to EQP output */ sqlite3_int64 nRow; /* Expected number of rows visited by scan */ int iId = pParse->iSelectId; /* Select id (left-most output column) */ int isSearch; /* True for a SEARCH. False for SCAN. */ if( (flags&WHERE_MULTI_OR) || (wctrlFlags&WHERE_ONETABLE_ONLY) ) return; isSearch = (pLevel->plan.nEq>0) || (flags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0 || (wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX)); zMsg = sqlite3MPrintf(db, "%s", isSearch?"SEARCH":"SCAN"); if( pItem->pSelect ){ zMsg = sqlite3MAppendf(db, zMsg, "%s SUBQUERY %d", zMsg,pItem->iSelectId); }else{ zMsg = sqlite3MAppendf(db, zMsg, "%s TABLE %s", zMsg, pItem->zName); } if( pItem->zAlias ){ zMsg = sqlite3MAppendf(db, zMsg, "%s AS %s", zMsg, pItem->zAlias); } if( (flags & WHERE_INDEXED)!=0 ){ char *zWhere = explainIndexRange(db, pLevel, pItem->pTab); zMsg = sqlite3MAppendf(db, zMsg, "%s USING %s%sINDEX%s%s%s", zMsg, ((flags & WHERE_TEMP_INDEX)?"AUTOMATIC ":""), ((flags & WHERE_IDX_ONLY)?"COVERING ":""), ((flags & WHERE_TEMP_INDEX)?"":" "), ((flags & WHERE_TEMP_INDEX)?"": pLevel->plan.u.pIdx->zName), zWhere ); sqlite3DbFree(db, zWhere); }else if( flags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){ zMsg = sqlite3MAppendf(db, zMsg, "%s USING INTEGER PRIMARY KEY", zMsg); if( flags&WHERE_ROWID_EQ ){ zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid=?)", zMsg); }else if( (flags&WHERE_BOTH_LIMIT)==WHERE_BOTH_LIMIT ){ zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid>? AND rowid<?)", zMsg); }else if( flags&WHERE_BTM_LIMIT ){ zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid>?)", zMsg); }else if( flags&WHERE_TOP_LIMIT ){ zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid<?)", zMsg); } } #ifndef SQLITE_OMIT_VIRTUALTABLE else if( (flags & WHERE_VIRTUALTABLE)!=0 ){ sqlite3_index_info *pVtabIdx = pLevel->plan.u.pVtabIdx; zMsg = sqlite3MAppendf(db, zMsg, "%s VIRTUAL TABLE INDEX %d:%s", zMsg, pVtabIdx->idxNum, pVtabIdx->idxStr); } #endif if( wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX) ){ testcase( wctrlFlags & WHERE_ORDERBY_MIN ); nRow = 1; }else{ nRow = (sqlite3_int64)pLevel->plan.nRow; } zMsg = sqlite3MAppendf(db, zMsg, "%s (~%lld rows)", zMsg, nRow); sqlite3VdbeAddOp4(v, OP_Explain, iId, iLevel, iFrom, zMsg, P4_DYNAMIC); } } #else # define explainOneScan(u,v,w,x,y,z) #endif /* SQLITE_OMIT_EXPLAIN */ /* ** Generate code for the start of the iLevel-th loop in the WHERE clause ** implementation described by pWInfo. */ static Bitmask codeOneLoopStart( WhereInfo *pWInfo, /* Complete information about the WHERE clause */ int iLevel, /* Which level of pWInfo->a[] should be coded */ u16 wctrlFlags, /* One of the WHERE_* flags defined in sqliteInt.h */ Bitmask notReady /* Which tables are currently available */ ){ int j, k; /* Loop counters */ int iCur; /* The VDBE cursor for the table */ int addrNxt; /* Where to jump to continue with the next IN case */ int omitTable; /* True if we use the index only */ int bRev; /* True if we need to scan in reverse order */ WhereLevel *pLevel; /* The where level to be coded */ WhereClause *pWC; /* Decomposition of the entire WHERE clause */ WhereTerm *pTerm; /* A WHERE clause term */ Parse *pParse; /* Parsing context */ Vdbe *v; /* The prepared stmt under constructions */ struct SrcList_item *pTabItem; /* FROM clause term being coded */ int addrBrk; /* Jump here to break out of the loop */ int addrCont; /* Jump here to continue with next cycle */ int iRowidReg = 0; /* Rowid is stored in this register, if not zero */ int iReleaseReg = 0; /* Temp register to free before returning */ pParse = pWInfo->pParse; v = pParse->pVdbe; pWC = pWInfo->pWC; pLevel = &pWInfo->a[iLevel]; pTabItem = &pWInfo->pTabList->a[pLevel->iFrom]; iCur = pTabItem->iCursor; bRev = (pLevel->plan.wsFlags & WHERE_REVERSE)!=0; omitTable = (pLevel->plan.wsFlags & WHERE_IDX_ONLY)!=0 && (wctrlFlags & WHERE_FORCE_TABLE)==0; /* Create labels for the "break" and "continue" instructions ** for the current loop. Jump to addrBrk to break out of a loop. ** Jump to cont to go immediately to the next iteration of the ** loop. ** ** When there is an IN operator, we also have a "addrNxt" label that ** means to continue with the next IN value combination. When ** there are no IN operators in the constraints, the "addrNxt" label ** is the same as "addrBrk". */ addrBrk = pLevel->addrBrk = pLevel->addrNxt = sqlite3VdbeMakeLabel(v); addrCont = pLevel->addrCont = sqlite3VdbeMakeLabel(v); /* If this is the right table of a LEFT OUTER JOIN, allocate and ** initialize a memory cell that records if this table matches any ** row of the left table of the join. */ if( pLevel->iFrom>0 && (pTabItem[0].jointype & JT_LEFT)!=0 ){ pLevel->iLeftJoin = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin); VdbeComment((v, "init LEFT JOIN no-match flag")); } #ifndef SQLITE_OMIT_VIRTUALTABLE if( (pLevel->plan.wsFlags & WHERE_VIRTUALTABLE)!=0 ){ /* Case 0: The table is a virtual-table. Use the VFilter and VNext ** to access the data. */ int iReg; /* P3 Value for OP_VFilter */ sqlite3_index_info *pVtabIdx = pLevel->plan.u.pVtabIdx; int nConstraint = pVtabIdx->nConstraint; struct sqlite3_index_constraint_usage *aUsage = pVtabIdx->aConstraintUsage; const struct sqlite3_index_constraint *aConstraint = pVtabIdx->aConstraint; sqlite3ExprCachePush(pParse); iReg = sqlite3GetTempRange(pParse, nConstraint+2); for(j=1; j<=nConstraint; j++){ for(k=0; k<nConstraint; k++){ if( aUsage[k].argvIndex==j ){ int iTerm = aConstraint[k].iTermOffset; sqlite3ExprCode(pParse, pWC->a[iTerm].pExpr->pRight, iReg+j+1); break; } } if( k==nConstraint ) break; } sqlite3VdbeAddOp2(v, OP_Integer, pVtabIdx->idxNum, iReg); sqlite3VdbeAddOp2(v, OP_Integer, j-1, iReg+1); sqlite3VdbeAddOp4(v, OP_VFilter, iCur, addrBrk, iReg, pVtabIdx->idxStr, pVtabIdx->needToFreeIdxStr ? P4_MPRINTF : P4_STATIC); pVtabIdx->needToFreeIdxStr = 0; for(j=0; j<nConstraint; j++){ if( aUsage[j].omit ){ int iTerm = aConstraint[j].iTermOffset; disableTerm(pLevel, &pWC->a[iTerm]); } } pLevel->op = OP_VNext; pLevel->p1 = iCur; pLevel->p2 = sqlite3VdbeCurrentAddr(v); sqlite3ReleaseTempRange(pParse, iReg, nConstraint+2); sqlite3ExprCachePop(pParse, 1); }else #endif /* SQLITE_OMIT_VIRTUALTABLE */ if( pLevel->plan.wsFlags & WHERE_ROWID_EQ ){ /* Case 1: We can directly reference a single row using an ** equality comparison against the ROWID field. Or ** we reference multiple rows using a "rowid IN (...)" ** construct. */ iReleaseReg = sqlite3GetTempReg(pParse); pTerm = findTerm(pWC, iCur, -1, notReady, WO_EQ|WO_IN, 0); assert( pTerm!=0 ); assert( pTerm->pExpr!=0 ); assert( pTerm->leftCursor==iCur ); assert( omitTable==0 ); testcase( pTerm->wtFlags & TERM_VIRTUAL ); /* EV: R-30575-11662 */ iRowidReg = codeEqualityTerm(pParse, pTerm, pLevel, iReleaseReg); addrNxt = pLevel->addrNxt; sqlite3VdbeAddOp2(v, OP_MustBeInt, iRowidReg, addrNxt); sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addrNxt, iRowidReg); sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg); VdbeComment((v, "pk")); pLevel->op = OP_Noop; }else if( pLevel->plan.wsFlags & WHERE_ROWID_RANGE ){ /* Case 2: We have an inequality comparison against the ROWID field. */ int testOp = OP_Noop; int start; int memEndValue = 0; WhereTerm *pStart, *pEnd; assert( omitTable==0 ); pStart = findTerm(pWC, iCur, -1, notReady, WO_GT|WO_GE, 0); pEnd = findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE, 0); if( bRev ){ pTerm = pStart; pStart = pEnd; pEnd = pTerm; } if( pStart ){ Expr *pX; /* The expression that defines the start bound */ int r1, rTemp; /* Registers for holding the start boundary */ /* The following constant maps TK_xx codes into corresponding ** seek opcodes. It depends on a particular ordering of TK_xx */ const u8 aMoveOp[] = { /* TK_GT */ OP_SeekGt, /* TK_LE */ OP_SeekLe, /* TK_LT */ OP_SeekLt, /* TK_GE */ OP_SeekGe }; assert( TK_LE==TK_GT+1 ); /* Make sure the ordering.. */ assert( TK_LT==TK_GT+2 ); /* ... of the TK_xx values... */ assert( TK_GE==TK_GT+3 ); /* ... is correcct. */ testcase( pStart->wtFlags & TERM_VIRTUAL ); /* EV: R-30575-11662 */ pX = pStart->pExpr; assert( pX!=0 ); assert( pStart->leftCursor==iCur ); r1 = sqlite3ExprCodeTemp(pParse, pX->pRight, &rTemp); sqlite3VdbeAddOp3(v, aMoveOp[pX->op-TK_GT], iCur, addrBrk, r1); VdbeComment((v, "pk")); sqlite3ExprCacheAffinityChange(pParse, r1, 1); sqlite3ReleaseTempReg(pParse, rTemp); disableTerm(pLevel, pStart); }else{ sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iCur, addrBrk); } if( pEnd ){ Expr *pX; pX = pEnd->pExpr; assert( pX!=0 ); assert( pEnd->leftCursor==iCur ); testcase( pEnd->wtFlags & TERM_VIRTUAL ); /* EV: R-30575-11662 */ memEndValue = ++pParse->nMem; sqlite3ExprCode(pParse, pX->pRight, memEndValue); if( pX->op==TK_LT || pX->op==TK_GT ){ testOp = bRev ? OP_Le : OP_Ge; }else{ testOp = bRev ? OP_Lt : OP_Gt; } disableTerm(pLevel, pEnd); } start = sqlite3VdbeCurrentAddr(v); pLevel->op = bRev ? OP_Prev : OP_Next; pLevel->p1 = iCur; pLevel->p2 = start; if( pStart==0 && pEnd==0 ){ pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP; }else{ assert( pLevel->p5==0 ); } if( testOp!=OP_Noop ){ iRowidReg = iReleaseReg = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp2(v, OP_Rowid, iCur, iRowidReg); sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg); sqlite3VdbeAddOp3(v, testOp, memEndValue, addrBrk, iRowidReg); sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC | SQLITE_JUMPIFNULL); } }else if( pLevel->plan.wsFlags & (WHERE_COLUMN_RANGE|WHERE_COLUMN_EQ) ){ /* Case 3: A scan using an index. ** ** The WHERE clause may contain zero or more equality ** terms ("==" or "IN" operators) that refer to the N ** left-most columns of the index. It may also contain ** inequality constraints (>, <, >= or <=) on the indexed ** column that immediately follows the N equalities. Only ** the right-most column can be an inequality - the rest must ** use the "==" and "IN" operators. For example, if the ** index is on (x,y,z), then the following clauses are all ** optimized: ** ** x=5 ** x=5 AND y=10 ** x=5 AND y<10 ** x=5 AND y>5 AND y<10 ** x=5 AND y=5 AND z<=10 ** ** The z<10 term of the following cannot be used, only ** the x=5 term: ** ** x=5 AND z<10 ** ** N may be zero if there are inequality constraints. ** If there are no inequality constraints, then N is at ** least one. ** ** This case is also used when there are no WHERE clause ** constraints but an index is selected anyway, in order ** to force the output order to conform to an ORDER BY. */ static const u8 aStartOp[] = { 0, 0, OP_Rewind, /* 2: (!start_constraints && startEq && !bRev) */ OP_Last, /* 3: (!start_constraints && startEq && bRev) */ OP_SeekGt, /* 4: (start_constraints && !startEq && !bRev) */ OP_SeekLt, /* 5: (start_constraints && !startEq && bRev) */ OP_SeekGe, /* 6: (start_constraints && startEq && !bRev) */ OP_SeekLe /* 7: (start_constraints && startEq && bRev) */ }; static const u8 aEndOp[] = { OP_Noop, /* 0: (!end_constraints) */ OP_IdxGE, /* 1: (end_constraints && !bRev) */ OP_IdxLT /* 2: (end_constraints && bRev) */ }; int nEq = pLevel->plan.nEq; /* Number of == or IN terms */ int isMinQuery = 0; /* If this is an optimized SELECT min(x).. */ int regBase; /* Base register holding constraint values */ int r1; /* Temp register */ WhereTerm *pRangeStart = 0; /* Inequality constraint at range start */ WhereTerm *pRangeEnd = 0; /* Inequality constraint at range end */ int startEq; /* True if range start uses ==, >= or <= */ int endEq; /* True if range end uses ==, >= or <= */ int start_constraints; /* Start of range is constrained */ int nConstraint; /* Number of constraint terms */ Index *pIdx; /* The index we will be using */ int iIdxCur; /* The VDBE cursor for the index */ int nExtraReg = 0; /* Number of extra registers needed */ int op; /* Instruction opcode */ char *zStartAff; /* Affinity for start of range constraint */ char *zEndAff; /* Affinity for end of range constraint */ pIdx = pLevel->plan.u.pIdx; iIdxCur = pLevel->iIdxCur; k = pIdx->aiColumn[nEq]; /* Column for inequality constraints */ /* If this loop satisfies a sort order (pOrderBy) request that ** was passed to this function to implement a "SELECT min(x) ..." ** query, then the caller will only allow the loop to run for ** a single iteration. This means that the first row returned ** should not have a NULL value stored in 'x'. If column 'x' is ** the first one after the nEq equality constraints in the index, ** this requires some special handling. */ if( (wctrlFlags&WHERE_ORDERBY_MIN)!=0 && (pLevel->plan.wsFlags&WHERE_ORDERBY) && (pIdx->nColumn>nEq) ){ /* assert( pOrderBy->nExpr==1 ); */ /* assert( pOrderBy->a[0].pExpr->iColumn==pIdx->aiColumn[nEq] ); */ isMinQuery = 1; nExtraReg = 1; } /* Find any inequality constraint terms for the start and end ** of the range. */ if( pLevel->plan.wsFlags & WHERE_TOP_LIMIT ){ pRangeEnd = findTerm(pWC, iCur, k, notReady, (WO_LT|WO_LE), pIdx); nExtraReg = 1; } if( pLevel->plan.wsFlags & WHERE_BTM_LIMIT ){ pRangeStart = findTerm(pWC, iCur, k, notReady, (WO_GT|WO_GE), pIdx); nExtraReg = 1; } /* Generate code to evaluate all constraint terms using == or IN ** and store the values of those terms in an array of registers ** starting at regBase. */ regBase = codeAllEqualityTerms( pParse, pLevel, pWC, notReady, nExtraReg, &zStartAff ); zEndAff = sqlite3DbStrDup(pParse->db, zStartAff); addrNxt = pLevel->addrNxt; /* If we are doing a reverse order scan on an ascending index, or ** a forward order scan on a descending index, interchange the ** start and end terms (pRangeStart and pRangeEnd). */ if( nEq<pIdx->nColumn && bRev==(pIdx->aSortOrder[nEq]==SQLITE_SO_ASC) ){ SWAP(WhereTerm *, pRangeEnd, pRangeStart); } testcase( pRangeStart && pRangeStart->eOperator & WO_LE ); testcase( pRangeStart && pRangeStart->eOperator & WO_GE ); testcase( pRangeEnd && pRangeEnd->eOperator & WO_LE ); testcase( pRangeEnd && pRangeEnd->eOperator & WO_GE ); startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE); endEq = !pRangeEnd || pRangeEnd->eOperator & (WO_LE|WO_GE); start_constraints = pRangeStart || nEq>0; /* Seek the index cursor to the start of the range. */ nConstraint = nEq; if( pRangeStart ){ Expr *pRight = pRangeStart->pExpr->pRight; sqlite3ExprCode(pParse, pRight, regBase+nEq); if( (pRangeStart->wtFlags & TERM_VNULL)==0 ){ sqlite3ExprCodeIsNullJump(v, pRight, regBase+nEq, addrNxt); } if( zStartAff ){ if( sqlite3CompareAffinity(pRight, zStartAff[nEq])==SQLITE_AFF_NONE){ /* Since the comparison is to be performed with no conversions ** applied to the operands, set the affinity to apply to pRight to ** SQLITE_AFF_NONE. */ zStartAff[nEq] = SQLITE_AFF_NONE; } if( sqlite3ExprNeedsNoAffinityChange(pRight, zStartAff[nEq]) ){ zStartAff[nEq] = SQLITE_AFF_NONE; } } nConstraint++; testcase( pRangeStart->wtFlags & TERM_VIRTUAL ); /* EV: R-30575-11662 */ }else if( isMinQuery ){ sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq); nConstraint++; startEq = 0; start_constraints = 1; } codeApplyAffinity(pParse, regBase, nConstraint, zStartAff); op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev]; assert( op!=0 ); testcase( op==OP_Rewind ); testcase( op==OP_Last ); testcase( op==OP_SeekGt ); testcase( op==OP_SeekGe ); testcase( op==OP_SeekLe ); testcase( op==OP_SeekLt ); sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint); /* Load the value for the inequality constraint at the end of the ** range (if any). */ nConstraint = nEq; if( pRangeEnd ){ Expr *pRight = pRangeEnd->pExpr->pRight; sqlite3ExprCacheRemove(pParse, regBase+nEq, 1); sqlite3ExprCode(pParse, pRight, regBase+nEq); if( (pRangeEnd->wtFlags & TERM_VNULL)==0 ){ sqlite3ExprCodeIsNullJump(v, pRight, regBase+nEq, addrNxt); } if( zEndAff ){ if( sqlite3CompareAffinity(pRight, zEndAff[nEq])==SQLITE_AFF_NONE){ /* Since the comparison is to be performed with no conversions ** applied to the operands, set the affinity to apply to pRight to ** SQLITE_AFF_NONE. */ zEndAff[nEq] = SQLITE_AFF_NONE; } if( sqlite3ExprNeedsNoAffinityChange(pRight, zEndAff[nEq]) ){ zEndAff[nEq] = SQLITE_AFF_NONE; } } codeApplyAffinity(pParse, regBase, nEq+1, zEndAff); nConstraint++; testcase( pRangeEnd->wtFlags & TERM_VIRTUAL ); /* EV: R-30575-11662 */ } sqlite3DbFree(pParse->db, zStartAff); sqlite3DbFree(pParse->db, zEndAff); /* Top of the loop body */ pLevel->p2 = sqlite3VdbeCurrentAddr(v); /* Check if the index cursor is past the end of the range. */ op = aEndOp[(pRangeEnd || nEq) * (1 + bRev)]; testcase( op==OP_Noop ); testcase( op==OP_IdxGE ); testcase( op==OP_IdxLT ); if( op!=OP_Noop ){ sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint); sqlite3VdbeChangeP5(v, endEq!=bRev ?1:0); } /* If there are inequality constraints, check that the value ** of the table column that the inequality contrains is not NULL. ** If it is, jump to the next iteration of the loop. */ r1 = sqlite3GetTempReg(pParse); testcase( pLevel->plan.wsFlags & WHERE_BTM_LIMIT ); testcase( pLevel->plan.wsFlags & WHERE_TOP_LIMIT ); if( (pLevel->plan.wsFlags & (WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0 ){ sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, nEq, r1); sqlite3VdbeAddOp2(v, OP_IsNull, r1, addrCont); } sqlite3ReleaseTempReg(pParse, r1); /* Seek the table cursor, if required */ disableTerm(pLevel, pRangeStart); disableTerm(pLevel, pRangeEnd); if( !omitTable ){ iRowidReg = iReleaseReg = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, iRowidReg); sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg); sqlite3VdbeAddOp2(v, OP_Seek, iCur, iRowidReg); /* Deferred seek */ } /* Record the instruction used to terminate the loop. Disable ** WHERE clause terms made redundant by the index range scan. */ if( pLevel->plan.wsFlags & WHERE_UNIQUE ){ pLevel->op = OP_Noop; }else if( bRev ){ pLevel->op = OP_Prev; }else{ pLevel->op = OP_Next; } pLevel->p1 = iIdxCur; }else #ifndef SQLITE_OMIT_OR_OPTIMIZATION if( pLevel->plan.wsFlags & WHERE_MULTI_OR ){ /* Case 4: Two or more separately indexed terms connected by OR ** ** Example: ** ** CREATE TABLE t1(a,b,c,d); ** CREATE INDEX i1 ON t1(a); ** CREATE INDEX i2 ON t1(b); ** CREATE INDEX i3 ON t1(c); ** ** SELECT * FROM t1 WHERE a=5 OR b=7 OR (c=11 AND d=13) ** ** In the example, there are three indexed terms connected by OR. ** The top of the loop looks like this: ** ** Null 1 # Zero the rowset in reg 1 ** ** Then, for each indexed term, the following. The arguments to ** RowSetTest are such that the rowid of the current row is inserted ** into the RowSet. If it is already present, control skips the ** Gosub opcode and jumps straight to the code generated by WhereEnd(). ** ** sqlite3WhereBegin(<term>) ** RowSetTest # Insert rowid into rowset ** Gosub 2 A ** sqlite3WhereEnd() ** ** Following the above, code to terminate the loop. Label A, the target ** of the Gosub above, jumps to the instruction right after the Goto. ** ** Null 1 # Zero the rowset in reg 1 ** Goto B # The loop is finished. ** ** A: <loop body> # Return data, whatever. ** ** Return 2 # Jump back to the Gosub ** ** B: <after the loop> ** */ WhereClause *pOrWc; /* The OR-clause broken out into subterms */ SrcList *pOrTab; /* Shortened table list or OR-clause generation */ int regReturn = ++pParse->nMem; /* Register used with OP_Gosub */ int regRowset = 0; /* Register for RowSet object */ int regRowid = 0; /* Register holding rowid */ int iLoopBody = sqlite3VdbeMakeLabel(v); /* Start of loop body */ int iRetInit; /* Address of regReturn init */ int untestedTerms = 0; /* Some terms not completely tested */ int ii; pTerm = pLevel->plan.u.pTerm; assert( pTerm!=0 ); assert( pTerm->eOperator==WO_OR ); assert( (pTerm->wtFlags & TERM_ORINFO)!=0 ); pOrWc = &pTerm->u.pOrInfo->wc; pLevel->op = OP_Return; pLevel->p1 = regReturn; /* Set up a new SrcList ni pOrTab containing the table being scanned ** by this loop in the a[0] slot and all notReady tables in a[1..] slots. ** This becomes the SrcList in the recursive call to sqlite3WhereBegin(). */ if( pWInfo->nLevel>1 ){ int nNotReady; /* The number of notReady tables */ struct SrcList_item *origSrc; /* Original list of tables */ nNotReady = pWInfo->nLevel - iLevel - 1; pOrTab = sqlite3StackAllocRaw(pParse->db, sizeof(*pOrTab)+ nNotReady*sizeof(pOrTab->a[0])); if( pOrTab==0 ) return notReady; pOrTab->nAlloc = (i16)(nNotReady + 1); pOrTab->nSrc = pOrTab->nAlloc; memcpy(pOrTab->a, pTabItem, sizeof(*pTabItem)); origSrc = pWInfo->pTabList->a; for(k=1; k<=nNotReady; k++){ memcpy(&pOrTab->a[k], &origSrc[pLevel[k].iFrom], sizeof(pOrTab->a[k])); } }else{ pOrTab = pWInfo->pTabList; } /* Initialize the rowset register to contain NULL. An SQL NULL is ** equivalent to an empty rowset. ** ** Also initialize regReturn to contain the address of the instruction ** immediately following the OP_Return at the bottom of the loop. This ** is required in a few obscure LEFT JOIN cases where control jumps ** over the top of the loop into the body of it. In this case the ** correct response for the end-of-loop code (the OP_Return) is to ** fall through to the next instruction, just as an OP_Next does if ** called on an uninitialized cursor. */ if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){ regRowset = ++pParse->nMem; regRowid = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset); } iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn); for(ii=0; ii<pOrWc->nTerm; ii++){ WhereTerm *pOrTerm = &pOrWc->a[ii]; if( pOrTerm->leftCursor==iCur || pOrTerm->eOperator==WO_AND ){ WhereInfo *pSubWInfo; /* Info for single OR-term scan */ /* Loop through table entries that match term pOrTerm. */ pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrTerm->pExpr, 0, WHERE_OMIT_OPEN | WHERE_OMIT_CLOSE | WHERE_FORCE_TABLE | WHERE_ONETABLE_ONLY); if( pSubWInfo ){ explainOneScan( pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0 ); if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){ int iSet = ((ii==pOrWc->nTerm-1)?-1:ii); int r; r = sqlite3ExprCodeGetColumn(pParse, pTabItem->pTab, -1, iCur, regRowid); sqlite3VdbeAddOp4Int(v, OP_RowSetTest, regRowset, sqlite3VdbeCurrentAddr(v)+2, r, iSet); } sqlite3VdbeAddOp2(v, OP_Gosub, regReturn, iLoopBody); /* The pSubWInfo->untestedTerms flag means that this OR term ** contained one or more AND term from a notReady table. The ** terms from the notReady table could not be tested and will ** need to be tested later. */ if( pSubWInfo->untestedTerms ) untestedTerms = 1; /* Finish the loop through table entries that match term pOrTerm. */ sqlite3WhereEnd(pSubWInfo); } } } sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v)); sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrBrk); sqlite3VdbeResolveLabel(v, iLoopBody); if( pWInfo->nLevel>1 ) sqlite3StackFree(pParse->db, pOrTab); if( !untestedTerms ) disableTerm(pLevel, pTerm); }else #endif /* SQLITE_OMIT_OR_OPTIMIZATION */ { /* Case 5: There is no usable index. We must do a complete ** scan of the entire table. */ static const u8 aStep[] = { OP_Next, OP_Prev }; static const u8 aStart[] = { OP_Rewind, OP_Last }; assert( bRev==0 || bRev==1 ); assert( omitTable==0 ); pLevel->op = aStep[bRev]; pLevel->p1 = iCur; pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk); pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP; } notReady &= ~getMask(pWC->pMaskSet, iCur); /* Insert code to test every subexpression that can be completely ** computed using the current set of tables. ** ** IMPLEMENTATION-OF: R-49525-50935 Terms that cannot be satisfied through ** the use of indices become tests that are evaluated against each row of ** the relevant input tables. */ for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){ Expr *pE; testcase( pTerm->wtFlags & TERM_VIRTUAL ); /* IMP: R-30575-11662 */ testcase( pTerm->wtFlags & TERM_CODED ); if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue; if( (pTerm->prereqAll & notReady)!=0 ){ testcase( pWInfo->untestedTerms==0 && (pWInfo->wctrlFlags & WHERE_ONETABLE_ONLY)!=0 ); pWInfo->untestedTerms = 1; continue; } pE = pTerm->pExpr; assert( pE!=0 ); if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){ continue; } sqlite3ExprIfFalse(pParse, pE, addrCont, SQLITE_JUMPIFNULL); pTerm->wtFlags |= TERM_CODED; } /* For a LEFT OUTER JOIN, generate code that will record the fact that ** at least one row of the right table has matched the left table. */ if( pLevel->iLeftJoin ){ pLevel->addrFirst = sqlite3VdbeCurrentAddr(v); sqlite3VdbeAddOp2(v, OP_Integer, 1, pLevel->iLeftJoin); VdbeComment((v, "record LEFT JOIN hit")); sqlite3ExprCacheClear(pParse); for(pTerm=pWC->a, j=0; j<pWC->nTerm; j++, pTerm++){ testcase( pTerm->wtFlags & TERM_VIRTUAL ); /* IMP: R-30575-11662 */ testcase( pTerm->wtFlags & TERM_CODED ); if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue; if( (pTerm->prereqAll & notReady)!=0 ){ assert( pWInfo->untestedTerms ); continue; } assert( pTerm->pExpr ); sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont, SQLITE_JUMPIFNULL); pTerm->wtFlags |= TERM_CODED; } } sqlite3ReleaseTempReg(pParse, iReleaseReg); return notReady; } #if defined(SQLITE_TEST) /* ** The following variable holds a text description of query plan generated ** by the most recent call to sqlite3WhereBegin(). Each call to WhereBegin ** overwrites the previous. This information is used for testing and ** analysis only. */ char sqlite3_query_plan[BMS*2*40]; /* Text of the join */ static int nQPlan = 0; /* Next free slow in _query_plan[] */ #endif /* SQLITE_TEST */ /* ** Free a WhereInfo structure */ static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){ if( ALWAYS(pWInfo) ){ int i; for(i=0; i<pWInfo->nLevel; i++){ sqlite3_index_info *pInfo = pWInfo->a[i].pIdxInfo; if( pInfo ){ /* assert( pInfo->needToFreeIdxStr==0 || db->mallocFailed ); */ if( pInfo->needToFreeIdxStr ){ sqlite3_free(pInfo->idxStr); } sqlite3DbFree(db, pInfo); } if( pWInfo->a[i].plan.wsFlags & WHERE_TEMP_INDEX ){ Index *pIdx = pWInfo->a[i].plan.u.pIdx; if( pIdx ){ sqlite3DbFree(db, pIdx->zColAff); sqlite3DbFree(db, pIdx); } } } whereClauseClear(pWInfo->pWC); sqlite3DbFree(db, pWInfo); } } /* ** Generate the beginning of the loop used for WHERE clause processing. ** The return value is a pointer to an opaque structure that contains ** information needed to terminate the loop. Later, the calling routine ** should invoke sqlite3WhereEnd() with the return value of this function ** in order to complete the WHERE clause processing. ** ** If an error occurs, this routine returns NULL. ** ** The basic idea is to do a nested loop, one loop for each table in ** the FROM clause of a select. (INSERT and UPDATE statements are the ** same as a SELECT with only a single table in the FROM clause.) For ** example, if the SQL is this: ** ** SELECT * FROM t1, t2, t3 WHERE ...; ** ** Then the code generated is conceptually like the following: ** ** foreach row1 in t1 do \ Code generated ** foreach row2 in t2 do |-- by sqlite3WhereBegin() ** foreach row3 in t3 do / ** ... ** end \ Code generated ** end |-- by sqlite3WhereEnd() ** end / ** ** Note that the loops might not be nested in the order in which they ** appear in the FROM clause if a different order is better able to make ** use of indices. Note also that when the IN operator appears in ** the WHERE clause, it might result in additional nested loops for ** scanning through all values on the right-hand side of the IN. ** ** There are Btree cursors associated with each table. t1 uses cursor ** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor. ** And so forth. This routine generates code to open those VDBE cursors ** and sqlite3WhereEnd() generates the code to close them. ** ** The code that sqlite3WhereBegin() generates leaves the cursors named ** in pTabList pointing at their appropriate entries. The [...] code ** can use OP_Column and OP_Rowid opcodes on these cursors to extract ** data from the various tables of the loop. ** ** If the WHERE clause is empty, the foreach loops must each scan their ** entire tables. Thus a three-way join is an O(N^3) operation. But if ** the tables have indices and there are terms in the WHERE clause that ** refer to those indices, a complete table scan can be avoided and the ** code will run much faster. Most of the work of this routine is checking ** to see if there are indices that can be used to speed up the loop. ** ** Terms of the WHERE clause are also used to limit which rows actually ** make it to the "..." in the middle of the loop. After each "foreach", ** terms of the WHERE clause that use only terms in that loop and outer ** loops are evaluated and if false a jump is made around all subsequent ** inner loops (or around the "..." if the test occurs within the inner- ** most loop) ** ** OUTER JOINS ** ** An outer join of tables t1 and t2 is conceptally coded as follows: ** ** foreach row1 in t1 do ** flag = 0 ** foreach row2 in t2 do ** start: ** ... ** flag = 1 ** end ** if flag==0 then ** move the row2 cursor to a null row ** goto start ** fi ** end ** ** ORDER BY CLAUSE PROCESSING ** ** *ppOrderBy is a pointer to the ORDER BY clause of a SELECT statement, ** if there is one. If there is no ORDER BY clause or if this routine ** is called from an UPDATE or DELETE statement, then ppOrderBy is NULL. ** ** If an index can be used so that the natural output order of the table ** scan is correct for the ORDER BY clause, then that index is used and ** *ppOrderBy is set to NULL. This is an optimization that prevents an ** unnecessary sort of the result set if an index appropriate for the ** ORDER BY clause already exists. ** ** If the where clause loops cannot be arranged to provide the correct ** output order, then the *ppOrderBy is unchanged. */ WhereInfo *sqlite3WhereBegin( Parse *pParse, /* The parser context */ SrcList *pTabList, /* A list of all tables to be scanned */ Expr *pWhere, /* The WHERE clause */ ExprList **ppOrderBy, /* An ORDER BY clause, or NULL */ u16 wctrlFlags /* One of the WHERE_* flags defined in sqliteInt.h */ ){ int i; /* Loop counter */ int nByteWInfo; /* Num. bytes allocated for WhereInfo struct */ int nTabList; /* Number of elements in pTabList */ WhereInfo *pWInfo; /* Will become the return value of this function */ Vdbe *v = pParse->pVdbe; /* The virtual database engine */ Bitmask notReady; /* Cursors that are not yet positioned */ WhereMaskSet *pMaskSet; /* The expression mask set */ WhereClause *pWC; /* Decomposition of the WHERE clause */ struct SrcList_item *pTabItem; /* A single entry from pTabList */ WhereLevel *pLevel; /* A single level in the pWInfo list */ int iFrom; /* First unused FROM clause element */ int andFlags; /* AND-ed combination of all pWC->a[].wtFlags */ sqlite3 *db; /* Database connection */ /* The number of tables in the FROM clause is limited by the number of ** bits in a Bitmask */ testcase( pTabList->nSrc==BMS ); if( pTabList->nSrc>BMS ){ sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS); return 0; } /* This function normally generates a nested loop for all tables in ** pTabList. But if the WHERE_ONETABLE_ONLY flag is set, then we should ** only generate code for the first table in pTabList and assume that ** any cursors associated with subsequent tables are uninitialized. */ nTabList = (wctrlFlags & WHERE_ONETABLE_ONLY) ? 1 : pTabList->nSrc; /* Allocate and initialize the WhereInfo structure that will become the ** return value. A single allocation is used to store the WhereInfo ** struct, the contents of WhereInfo.a[], the WhereClause structure ** and the WhereMaskSet structure. Since WhereClause contains an 8-byte ** field (type Bitmask) it must be aligned on an 8-byte boundary on ** some architectures. Hence the ROUND8() below. */ db = pParse->db; nByteWInfo = ROUND8(sizeof(WhereInfo)+(nTabList-1)*sizeof(WhereLevel)); pWInfo = sqlite3DbMallocZero(db, nByteWInfo + sizeof(WhereClause) + sizeof(WhereMaskSet) ); if( db->mallocFailed ){ sqlite3DbFree(db, pWInfo); pWInfo = 0; goto whereBeginError; } pWInfo->nLevel = nTabList; pWInfo->pParse = pParse; pWInfo->pTabList = pTabList; pWInfo->iBreak = sqlite3VdbeMakeLabel(v); pWInfo->pWC = pWC = (WhereClause *)&((u8 *)pWInfo)[nByteWInfo]; pWInfo->wctrlFlags = wctrlFlags; pWInfo->savedNQueryLoop = pParse->nQueryLoop; pMaskSet = (WhereMaskSet*)&pWC[1]; /* Split the WHERE clause into separate subexpressions where each ** subexpression is separated by an AND operator. */ initMaskSet(pMaskSet); whereClauseInit(pWC, pParse, pMaskSet); sqlite3ExprCodeConstants(pParse, pWhere); whereSplit(pWC, pWhere, TK_AND); /* IMP: R-15842-53296 */ /* Special case: a WHERE clause that is constant. Evaluate the ** expression and either jump over all of the code or fall thru. */ if( pWhere && (nTabList==0 || sqlite3ExprIsConstantNotJoin(pWhere)) ){ sqlite3ExprIfFalse(pParse, pWhere, pWInfo->iBreak, SQLITE_JUMPIFNULL); pWhere = 0; } /* Assign a bit from the bitmask to every term in the FROM clause. ** ** When assigning bitmask values to FROM clause cursors, it must be ** the case that if X is the bitmask for the N-th FROM clause term then ** the bitmask for all FROM clause terms to the left of the N-th term ** is (X-1). An expression from the ON clause of a LEFT JOIN can use ** its Expr.iRightJoinTable value to find the bitmask of the right table ** of the join. Subtracting one from the right table bitmask gives a ** bitmask for all tables to the left of the join. Knowing the bitmask ** for all tables to the left of a left join is important. Ticket #3015. ** ** Configure the WhereClause.vmask variable so that bits that correspond ** to virtual table cursors are set. This is used to selectively disable ** the OR-to-IN transformation in exprAnalyzeOrTerm(). It is not helpful ** with virtual tables. ** ** Note that bitmasks are created for all pTabList->nSrc tables in ** pTabList, not just the first nTabList tables. nTabList is normally ** equal to pTabList->nSrc but might be shortened to 1 if the ** WHERE_ONETABLE_ONLY flag is set. */ assert( pWC->vmask==0 && pMaskSet->n==0 ); for(i=0; i<pTabList->nSrc; i++){ createMask(pMaskSet, pTabList->a[i].iCursor); #ifndef SQLITE_OMIT_VIRTUALTABLE if( ALWAYS(pTabList->a[i].pTab) && IsVirtual(pTabList->a[i].pTab) ){ pWC->vmask |= ((Bitmask)1 << i); } #endif } #ifndef NDEBUG { Bitmask toTheLeft = 0; for(i=0; i<pTabList->nSrc; i++){ Bitmask m = getMask(pMaskSet, pTabList->a[i].iCursor); assert( (m-1)==toTheLeft ); toTheLeft |= m; } } #endif /* Analyze all of the subexpressions. Note that exprAnalyze() might ** add new virtual terms onto the end of the WHERE clause. We do not ** want to analyze these virtual terms, so start analyzing at the end ** and work forward so that the added virtual terms are never processed. */ exprAnalyzeAll(pTabList, pWC); if( db->mallocFailed ){ goto whereBeginError; } /* Chose the best index to use for each table in the FROM clause. ** ** This loop fills in the following fields: ** ** pWInfo->a[].pIdx The index to use for this level of the loop. ** pWInfo->a[].wsFlags WHERE_xxx flags associated with pIdx ** pWInfo->a[].nEq The number of == and IN constraints ** pWInfo->a[].iFrom Which term of the FROM clause is being coded ** pWInfo->a[].iTabCur The VDBE cursor for the database table ** pWInfo->a[].iIdxCur The VDBE cursor for the index ** pWInfo->a[].pTerm When wsFlags==WO_OR, the OR-clause term ** ** This loop also figures out the nesting order of tables in the FROM ** clause. */ notReady = ~(Bitmask)0; andFlags = ~0; WHERETRACE(("*** Optimizer Start ***\n")); for(i=iFrom=0, pLevel=pWInfo->a; i<nTabList; i++, pLevel++){ WhereCost bestPlan; /* Most efficient plan seen so far */ Index *pIdx; /* Index for FROM table at pTabItem */ int j; /* For looping over FROM tables */ int bestJ = -1; /* The value of j */ Bitmask m; /* Bitmask value for j or bestJ */ int isOptimal; /* Iterator for optimal/non-optimal search */ int nUnconstrained; /* Number tables without INDEXED BY */ Bitmask notIndexed; /* Mask of tables that cannot use an index */ memset(&bestPlan, 0, sizeof(bestPlan)); bestPlan.rCost = SQLITE_BIG_DBL; WHERETRACE(("*** Begin search for loop %d ***\n", i)); /* Loop through the remaining entries in the FROM clause to find the ** next nested loop. The loop tests all FROM clause entries ** either once or twice. ** ** The first test is always performed if there are two or more entries ** remaining and never performed if there is only one FROM clause entry ** to choose from. The first test looks for an "optimal" scan. In ** this context an optimal scan is one that uses the same strategy ** for the given FROM clause entry as would be selected if the entry ** were used as the innermost nested loop. In other words, a table ** is chosen such that the cost of running that table cannot be reduced ** by waiting for other tables to run first. This "optimal" test works ** by first assuming that the FROM clause is on the inner loop and finding ** its query plan, then checking to see if that query plan uses any ** other FROM clause terms that are notReady. If no notReady terms are ** used then the "optimal" query plan works. ** ** Note that the WhereCost.nRow parameter for an optimal scan might ** not be as small as it would be if the table really were the innermost ** join. The nRow value can be reduced by WHERE clause constraints ** that do not use indices. But this nRow reduction only happens if the ** table really is the innermost join. ** ** The second loop iteration is only performed if no optimal scan ** strategies were found by the first iteration. This second iteration ** is used to search for the lowest cost scan overall. ** ** Previous versions of SQLite performed only the second iteration - ** the next outermost loop was always that with the lowest overall ** cost. However, this meant that SQLite could select the wrong plan ** for scripts such as the following: ** ** CREATE TABLE t1(a, b); ** CREATE TABLE t2(c, d); ** SELECT * FROM t2, t1 WHERE t2.rowid = t1.a; ** ** The best strategy is to iterate through table t1 first. However it ** is not possible to determine this with a simple greedy algorithm. ** Since the cost of a linear scan through table t2 is the same ** as the cost of a linear scan through table t1, a simple greedy ** algorithm may choose to use t2 for the outer loop, which is a much ** costlier approach. */ nUnconstrained = 0; notIndexed = 0; for(isOptimal=(iFrom<nTabList-1); isOptimal>=0 && bestJ<0; isOptimal--){ Bitmask mask; /* Mask of tables not yet ready */ for(j=iFrom, pTabItem=&pTabList->a[j]; j<nTabList; j++, pTabItem++){ int doNotReorder; /* True if this table should not be reordered */ WhereCost sCost; /* Cost information from best[Virtual]Index() */ ExprList *pOrderBy; /* ORDER BY clause for index to optimize */ doNotReorder = (pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0; if( j!=iFrom && doNotReorder ) break; m = getMask(pMaskSet, pTabItem->iCursor); if( (m & notReady)==0 ){ if( j==iFrom ) iFrom++; continue; } mask = (isOptimal ? m : notReady); pOrderBy = ((i==0 && ppOrderBy )?*ppOrderBy:0); if( pTabItem->pIndex==0 ) nUnconstrained++; WHERETRACE(("=== trying table %d with isOptimal=%d ===\n", j, isOptimal)); assert( pTabItem->pTab ); #ifndef SQLITE_OMIT_VIRTUALTABLE if( IsVirtual(pTabItem->pTab) ){ sqlite3_index_info **pp = &pWInfo->a[j].pIdxInfo; bestVirtualIndex(pParse, pWC, pTabItem, mask, notReady, pOrderBy, &sCost, pp); }else #endif { bestBtreeIndex(pParse, pWC, pTabItem, mask, notReady, pOrderBy, &sCost); } assert( isOptimal || (sCost.used¬Ready)==0 ); /* If an INDEXED BY clause is present, then the plan must use that ** index if it uses any index at all */ assert( pTabItem->pIndex==0 || (sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 || sCost.plan.u.pIdx==pTabItem->pIndex ); if( isOptimal && (sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ){ notIndexed |= m; } /* Conditions under which this table becomes the best so far: ** ** (1) The table must not depend on other tables that have not ** yet run. ** ** (2) A full-table-scan plan cannot supercede indexed plan unless ** the full-table-scan is an "optimal" plan as defined above. ** ** (3) All tables have an INDEXED BY clause or this table lacks an ** INDEXED BY clause or this table uses the specific ** index specified by its INDEXED BY clause. This rule ensures ** that a best-so-far is always selected even if an impossible ** combination of INDEXED BY clauses are given. The error ** will be detected and relayed back to the application later. ** The NEVER() comes about because rule (2) above prevents ** An indexable full-table-scan from reaching rule (3). ** ** (4) The plan cost must be lower than prior plans or else the ** cost must be the same and the number of rows must be lower. */ if( (sCost.used¬Ready)==0 /* (1) */ && (bestJ<0 || (notIndexed&m)!=0 /* (2) */ || (bestPlan.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 || (sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0) && (nUnconstrained==0 || pTabItem->pIndex==0 /* (3) */ || NEVER((sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0)) && (bestJ<0 || sCost.rCost<bestPlan.rCost /* (4) */ || (sCost.rCost<=bestPlan.rCost && sCost.plan.nRow<bestPlan.plan.nRow)) ){ WHERETRACE(("=== table %d is best so far" " with cost=%g and nRow=%g\n", j, sCost.rCost, sCost.plan.nRow)); bestPlan = sCost; bestJ = j; } if( doNotReorder ) break; } } assert( bestJ>=0 ); assert( notReady & getMask(pMaskSet, pTabList->a[bestJ].iCursor) ); WHERETRACE(("*** Optimizer selects table %d for loop %d" " with cost=%g and nRow=%g\n", bestJ, pLevel-pWInfo->a, bestPlan.rCost, bestPlan.plan.nRow)); if( (bestPlan.plan.wsFlags & WHERE_ORDERBY)!=0 ){ *ppOrderBy = 0; } andFlags &= bestPlan.plan.wsFlags; pLevel->plan = bestPlan.plan; testcase( bestPlan.plan.wsFlags & WHERE_INDEXED ); testcase( bestPlan.plan.wsFlags & WHERE_TEMP_INDEX ); if( bestPlan.plan.wsFlags & (WHERE_INDEXED|WHERE_TEMP_INDEX) ){ pLevel->iIdxCur = pParse->nTab++; }else{ pLevel->iIdxCur = -1; } notReady &= ~getMask(pMaskSet, pTabList->a[bestJ].iCursor); pLevel->iFrom = (u8)bestJ; if( bestPlan.plan.nRow>=(double)1 ){ pParse->nQueryLoop *= bestPlan.plan.nRow; } /* Check that if the table scanned by this loop iteration had an ** INDEXED BY clause attached to it, that the named index is being ** used for the scan. If not, then query compilation has failed. ** Return an error. */ pIdx = pTabList->a[bestJ].pIndex; if( pIdx ){ if( (bestPlan.plan.wsFlags & WHERE_INDEXED)==0 ){ sqlite3ErrorMsg(pParse, "cannot use index: %s", pIdx->zName); goto whereBeginError; }else{ /* If an INDEXED BY clause is used, the bestIndex() function is ** guaranteed to find the index specified in the INDEXED BY clause ** if it find an index at all. */ assert( bestPlan.plan.u.pIdx==pIdx ); } } } WHERETRACE(("*** Optimizer Finished ***\n")); if( pParse->nErr || db->mallocFailed ){ goto whereBeginError; } /* If the total query only selects a single row, then the ORDER BY ** clause is irrelevant. */ if( (andFlags & WHERE_UNIQUE)!=0 && ppOrderBy ){ *ppOrderBy = 0; } /* If the caller is an UPDATE or DELETE statement that is requesting ** to use a one-pass algorithm, determine if this is appropriate. ** The one-pass algorithm only works if the WHERE clause constraints ** the statement to update a single row. */ assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 ); if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 && (andFlags & WHERE_UNIQUE)!=0 ){ pWInfo->okOnePass = 1; pWInfo->a[0].plan.wsFlags &= ~WHERE_IDX_ONLY; } /* Open all tables in the pTabList and any indices selected for ** searching those tables. */ sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */ notReady = ~(Bitmask)0; pWInfo->nRowOut = (double)1; for(i=0, pLevel=pWInfo->a; i<nTabList; i++, pLevel++){ Table *pTab; /* Table to open */ int iDb; /* Index of database containing table/index */ pTabItem = &pTabList->a[pLevel->iFrom]; pTab = pTabItem->pTab; pLevel->iTabCur = pTabItem->iCursor; pWInfo->nRowOut *= pLevel->plan.nRow; iDb = sqlite3SchemaToIndex(db, pTab->pSchema); if( (pTab->tabFlags & TF_Ephemeral)!=0 || pTab->pSelect ){ /* Do nothing */ }else #ifndef SQLITE_OMIT_VIRTUALTABLE if( (pLevel->plan.wsFlags & WHERE_VIRTUALTABLE)!=0 ){ const char *pVTab = (const char *)sqlite3GetVTable(db, pTab); int iCur = pTabItem->iCursor; sqlite3VdbeAddOp4(v, OP_VOpen, iCur, 0, 0, pVTab, P4_VTAB); }else #endif if( (pLevel->plan.wsFlags & WHERE_IDX_ONLY)==0 && (wctrlFlags & WHERE_OMIT_OPEN)==0 ){ int op = pWInfo->okOnePass ? OP_OpenWrite : OP_OpenRead; sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op); testcase( pTab->nCol==BMS-1 ); testcase( pTab->nCol==BMS ); if( !pWInfo->okOnePass && pTab->nCol<BMS ){ Bitmask b = pTabItem->colUsed; int n = 0; for(; b; b=b>>1, n++){} sqlite3VdbeChangeP4(v, sqlite3VdbeCurrentAddr(v)-1, SQLITE_INT_TO_PTR(n), P4_INT32); assert( n<=pTab->nCol ); } }else{ sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName); } #ifndef SQLITE_OMIT_AUTOMATIC_INDEX if( (pLevel->plan.wsFlags & WHERE_TEMP_INDEX)!=0 ){ constructAutomaticIndex(pParse, pWC, pTabItem, notReady, pLevel); }else #endif if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){ Index *pIx = pLevel->plan.u.pIdx; KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIx); int iIdxCur = pLevel->iIdxCur; assert( pIx->pSchema==pTab->pSchema ); assert( iIdxCur>=0 ); sqlite3VdbeAddOp4(v, OP_OpenRead, iIdxCur, pIx->tnum, iDb, (char*)pKey, P4_KEYINFO_HANDOFF); VdbeComment((v, "%s", pIx->zName)); } sqlite3CodeVerifySchema(pParse, iDb); notReady &= ~getMask(pWC->pMaskSet, pTabItem->iCursor); } pWInfo->iTop = sqlite3VdbeCurrentAddr(v); if( db->mallocFailed ) goto whereBeginError; /* Generate the code to do the search. Each iteration of the for ** loop below generates code for a single nested loop of the VM ** program. */ notReady = ~(Bitmask)0; for(i=0; i<nTabList; i++){ pLevel = &pWInfo->a[i]; explainOneScan(pParse, pTabList, pLevel, i, pLevel->iFrom, wctrlFlags); notReady = codeOneLoopStart(pWInfo, i, wctrlFlags, notReady); pWInfo->iContinue = pLevel->addrCont; } #ifdef SQLITE_TEST /* For testing and debugging use only */ /* Record in the query plan information about the current table ** and the index used to access it (if any). If the table itself ** is not used, its name is just '{}'. If no index is used ** the index is listed as "{}". If the primary key is used the ** index name is '*'. */ for(i=0; i<nTabList; i++){ char *z; int n; pLevel = &pWInfo->a[i]; pTabItem = &pTabList->a[pLevel->iFrom]; z = pTabItem->zAlias; if( z==0 ) z = pTabItem->pTab->zName; n = sqlite3Strlen30(z); if( n+nQPlan < sizeof(sqlite3_query_plan)-10 ){ if( pLevel->plan.wsFlags & WHERE_IDX_ONLY ){ memcpy(&sqlite3_query_plan[nQPlan], "{}", 2); nQPlan += 2; }else{ memcpy(&sqlite3_query_plan[nQPlan], z, n); nQPlan += n; } sqlite3_query_plan[nQPlan++] = ' '; } testcase( pLevel->plan.wsFlags & WHERE_ROWID_EQ ); testcase( pLevel->plan.wsFlags & WHERE_ROWID_RANGE ); if( pLevel->plan.wsFlags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){ memcpy(&sqlite3_query_plan[nQPlan], "* ", 2); nQPlan += 2; }else if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){ n = sqlite3Strlen30(pLevel->plan.u.pIdx->zName); if( n+nQPlan < sizeof(sqlite3_query_plan)-2 ){ memcpy(&sqlite3_query_plan[nQPlan], pLevel->plan.u.pIdx->zName, n); nQPlan += n; sqlite3_query_plan[nQPlan++] = ' '; } }else{ memcpy(&sqlite3_query_plan[nQPlan], "{} ", 3); nQPlan += 3; } } while( nQPlan>0 && sqlite3_query_plan[nQPlan-1]==' ' ){ sqlite3_query_plan[--nQPlan] = 0; } sqlite3_query_plan[nQPlan] = 0; nQPlan = 0; #endif /* SQLITE_TEST // Testing and debugging use only */ /* Record the continuation address in the WhereInfo structure. Then ** clean up and return. */ return pWInfo; /* Jump here if malloc fails */ whereBeginError: if( pWInfo ){ pParse->nQueryLoop = pWInfo->savedNQueryLoop; whereInfoFree(db, pWInfo); } return 0; } /* ** Generate the end of the WHERE loop. See comments on ** sqlite3WhereBegin() for additional information. */ void sqlite3WhereEnd(WhereInfo *pWInfo){ Parse *pParse = pWInfo->pParse; Vdbe *v = pParse->pVdbe; int i; WhereLevel *pLevel; SrcList *pTabList = pWInfo->pTabList; sqlite3 *db = pParse->db; /* Generate loop termination code. */ sqlite3ExprCacheClear(pParse); for(i=pWInfo->nLevel-1; i>=0; i--){ pLevel = &pWInfo->a[i]; sqlite3VdbeResolveLabel(v, pLevel->addrCont); if( pLevel->op!=OP_Noop ){ sqlite3VdbeAddOp2(v, pLevel->op, pLevel->p1, pLevel->p2); sqlite3VdbeChangeP5(v, pLevel->p5); } if( pLevel->plan.wsFlags & WHERE_IN_ABLE && pLevel->u.in.nIn>0 ){ struct InLoop *pIn; int j; sqlite3VdbeResolveLabel(v, pLevel->addrNxt); for(j=pLevel->u.in.nIn, pIn=&pLevel->u.in.aInLoop[j-1]; j>0; j--, pIn--){ sqlite3VdbeJumpHere(v, pIn->addrInTop+1); sqlite3VdbeAddOp2(v, OP_Next, pIn->iCur, pIn->addrInTop); sqlite3VdbeJumpHere(v, pIn->addrInTop-1); } sqlite3DbFree(db, pLevel->u.in.aInLoop); } sqlite3VdbeResolveLabel(v, pLevel->addrBrk); if( pLevel->iLeftJoin ){ int addr; addr = sqlite3VdbeAddOp1(v, OP_IfPos, pLevel->iLeftJoin); assert( (pLevel->plan.wsFlags & WHERE_IDX_ONLY)==0 || (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ); if( (pLevel->plan.wsFlags & WHERE_IDX_ONLY)==0 ){ sqlite3VdbeAddOp1(v, OP_NullRow, pTabList->a[i].iCursor); } if( pLevel->iIdxCur>=0 ){ sqlite3VdbeAddOp1(v, OP_NullRow, pLevel->iIdxCur); } if( pLevel->op==OP_Return ){ sqlite3VdbeAddOp2(v, OP_Gosub, pLevel->p1, pLevel->addrFirst); }else{ sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrFirst); } sqlite3VdbeJumpHere(v, addr); } } /* The "break" point is here, just past the end of the outer loop. ** Set it. */ sqlite3VdbeResolveLabel(v, pWInfo->iBreak); /* Close all of the cursors that were opened by sqlite3WhereBegin. */ assert( pWInfo->nLevel==1 || pWInfo->nLevel==pTabList->nSrc ); for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){ struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom]; Table *pTab = pTabItem->pTab; assert( pTab!=0 ); if( (pTab->tabFlags & TF_Ephemeral)==0 && pTab->pSelect==0 && (pWInfo->wctrlFlags & WHERE_OMIT_CLOSE)==0 ){ int ws = pLevel->plan.wsFlags; if( !pWInfo->okOnePass && (ws & WHERE_IDX_ONLY)==0 ){ sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor); } if( (ws & WHERE_INDEXED)!=0 && (ws & WHERE_TEMP_INDEX)==0 ){ sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur); } } /* If this scan uses an index, make code substitutions to read data ** from the index in preference to the table. Sometimes, this means ** the table need never be read from. This is a performance boost, ** as the vdbe level waits until the table is read before actually ** seeking the table cursor to the record corresponding to the current ** position in the index. ** ** Calls to the code generator in between sqlite3WhereBegin and ** sqlite3WhereEnd will have created code that references the table ** directly. This loop scans all that code looking for opcodes ** that reference the table and converts them into opcodes that ** reference the index. */ if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 && !db->mallocFailed){ int k, j, last; VdbeOp *pOp; Index *pIdx = pLevel->plan.u.pIdx; assert( pIdx!=0 ); pOp = sqlite3VdbeGetOp(v, pWInfo->iTop); last = sqlite3VdbeCurrentAddr(v); for(k=pWInfo->iTop; k<last; k++, pOp++){ if( pOp->p1!=pLevel->iTabCur ) continue; if( pOp->opcode==OP_Column ){ for(j=0; j<pIdx->nColumn; j++){ if( pOp->p2==pIdx->aiColumn[j] ){ pOp->p2 = j; pOp->p1 = pLevel->iIdxCur; break; } } assert( (pLevel->plan.wsFlags & WHERE_IDX_ONLY)==0 || j<pIdx->nColumn ); }else if( pOp->opcode==OP_Rowid ){ pOp->p1 = pLevel->iIdxCur; pOp->opcode = OP_IdxRowid; } } } } /* Final cleanup */ pParse->nQueryLoop = pWInfo->savedNQueryLoop; whereInfoFree(db, pWInfo); return; }