** so is applicable. Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
**
-** $Id: where.c,v 1.337 2008/12/12 17:56:16 drh Exp $
+** $Id: where.c,v 1.338 2008/12/17 19:22:16 drh Exp $
*/
#include "sqliteInt.h"
*/
typedef struct WhereClause WhereClause;
typedef struct ExprMaskSet ExprMaskSet;
+typedef struct WhereOrInfo WhereOrInfo;
+typedef struct WhereAndInfo WhereAndInfo;
/*
** The query generator uses an array of instances of this structure to
** X <op> <expr>
**
** where X is a column name and <op> is one of certain operators,
-** then WhereTerm.leftCursor and WhereTerm.leftColumn record the
-** cursor number and column number for X. WhereTerm.operator records
+** 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.
**
-** prereqRight and prereqAll record sets of cursor numbers,
+** 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 ExprMaskSet 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
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>" */
- int leftColumn; /* Column 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 */
#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_OR_OK 0x10 /* Used during OR-clause processing */
+#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 */
/*
** An instance of the following structure holds all information about a
WhereTerm aStatic[4]; /* Initial static space for a[] */
};
+/*
+** 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; /* The OR subexpression broken out */
+ double cost; /* Cost of evaluating this OR subexpression */
+};
+
+/*
+** 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 OR subexpression broken out */
+ Index *pIdx; /* Index to use */
+ double cost; /* Cost of evaluating this OR subexpression */
+};
+
/*
** An instance of the following structure keeps track of a mapping
** between VDBE cursor numbers and bits of the bitmasks in WhereTerm.
#define WO_GE (WO_EQ<<(TK_GE-TK_EQ))
#define WO_MATCH 0x040
#define WO_ISNULL 0x080
-#define WO_OR 0x100
+#define WO_OR 0x100 /* Two or more OR-connected terms */
+#define WO_AND 0x200 /* Two or more AND-connected terms */
#define WO_ALL 0xfff /* Mask of all possible WO_* values */
/*
-** Value for wsFlags returned by bestIndex(). These flags determine which
-** search strategies are appropriate.
+** 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.wtFlags field is usually set to WO_IN|WO_EQ|WO_ISNULL.
-** But if the table is the right table of a left join, WhereLevel.wtFlags
-** is set to WO_IN|WO_EQ. The WhereLevel.wtFlags field can then be used as
+** 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.
pWC->a = pWC->aStatic;
}
+/* Forward reference */
+static void whereClauseClear(WhereClause*);
+
+/*
+** Deallocate all memory associated with a WhereOrInfo object.
+*/
+static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){
+ if( p ){
+ whereClauseClear(&p->wc);
+ }
+}
+
+/*
+** Deallocate all memory associated with a WhereAndInfo object.
+*/
+static void whereAndInfoDelete(sqlite3 *db, WhereAndInfo *p){
+ if( p ){
+ whereClauseClear(&p->wc);
+ }
+}
+
/*
** Deallocate a WhereClause structure. The WhereClause structure
** itself is not freed. This routine is the inverse of whereClauseInit().
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);
for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){
if( pTerm->leftCursor==iCur
&& (pTerm->prereqRight & notReady)==0
- && pTerm->leftColumn==iColumn
+ && pTerm->u.leftColumn==iColumn
&& (pTerm->eOperator & op)!=0
){
if( pIdx && pTerm->eOperator!=WO_ISNULL ){
if( pOrTerm->leftCursor!=iCursor ){
return 0;
}
- if( pOrTerm->leftColumn!=iColumn ){
+ if( pOrTerm->u.leftColumn!=iColumn ){
return 0;
}
affRight = sqlite3ExprAffinity(pOrTerm->pExpr->pRight);
Expr *pRight = pExpr->pRight;
if( pLeft->op==TK_COLUMN ){
pTerm->leftCursor = pLeft->iTable;
- pTerm->leftColumn = pLeft->iColumn;
+ pTerm->u.leftColumn = pLeft->iColumn;
pTerm->eOperator = operatorMask(op);
}
if( pRight && pRight->op==TK_COLUMN ){
exprCommute(pParse, pDup);
pLeft = pDup->pLeft;
pNew->leftCursor = pLeft->iTable;
- pNew->leftColumn = pLeft->iColumn;
+ pNew->u.leftColumn = pLeft->iColumn;
pNew->prereqRight = prereqLeft;
pNew->prereqAll = prereqAll;
pNew->eOperator = operatorMask(pDup->op);
if( db->mallocFailed ) goto or_not_possible;
do{
assert( j<sOr.nTerm );
- iColumn = sOr.a[j].leftColumn;
+ iColumn = sOr.a[j].u.leftColumn;
iCursor = sOr.a[j].leftCursor;
ok = iCursor>=0;
for(i=sOr.nTerm-1, pOrTerm=sOr.a; i>=0 && ok; i--, pOrTerm++){
pNewTerm = &pWC->a[idxNew];
pNewTerm->prereqRight = prereqExpr;
pNewTerm->leftCursor = pLeft->iTable;
- pNewTerm->leftColumn = pLeft->iColumn;
+ pNewTerm->u.leftColumn = pLeft->iColumn;
pNewTerm->eOperator = WO_MATCH;
pNewTerm->iParent = idxTerm;
pTerm = &pWC->a[idxTerm];
testcase( pTerm->eOperator==WO_IN );
testcase( pTerm->eOperator==WO_ISNULL );
if( pTerm->eOperator & (WO_IN|WO_ISNULL) ) continue;
- pIdxCons[j].iColumn = pTerm->leftColumn;
+ 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
if( pTerm ){
if( findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE, 0) ){
wsFlags |= WHERE_TOP_LIMIT;
- cost /= 3; /* Guess that rowid<EXPR eliminates two-thirds or rows */
+ cost /= 3; /* Guess that rowid<EXPR eliminates two-thirds of rows */
}
if( findTerm(pWC, iCur, -1, notReady, WO_GT|WO_GE, 0) ){
wsFlags |= WHERE_BTM_LIMIT;
** 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.
**
-** This routine always allocates at least one memory cell and puts
-** the address of that memory cell in pLevel->iMem. The code that
-** calls this routine will use pLevel->iMem to store the termination
+** 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.
** value. If there are IN operators we'll need one for each == or
** IN constraint.
*/
- pLevel->iMem = pParse->nMem + 1;
- regBase = pParse->nMem + 2;
- pParse->nMem += pLevel->nEq + 2 + nExtraReg;
+ regBase = pParse->nMem + 1;
+ pParse->nMem += pLevel->nEq + 1 + nExtraReg;
/* Evaluate the equality constraints
*/
*/
int testOp = OP_Noop;
int start;
+ int memEndValue = 0;
WhereTerm *pStart, *pEnd;
assert( omitTable==0 );
pX = pEnd->pExpr;
assert( pX!=0 );
assert( pEnd->leftCursor==iCur );
- pLevel->iMem = ++pParse->nMem;
- sqlite3ExprCode(pParse, pX->pRight, pLevel->iMem);
+ memEndValue = ++pParse->nMem;
+ sqlite3ExprCode(pParse, pX->pRight, memEndValue);
if( pX->op==TK_LT || pX->op==TK_GT ){
testOp = bRev ? OP_Le : OP_Ge;
}else{
if( testOp!=OP_Noop ){
int r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp2(v, OP_Rowid, iCur, r1);
- /* sqlite3VdbeAddOp2(v, OP_SCopy, pLevel->iMem, 0); */
- sqlite3VdbeAddOp3(v, testOp, pLevel->iMem, addrBrk, r1);
+ sqlite3VdbeAddOp3(v, testOp, memEndValue, addrBrk, r1);
sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC | SQLITE_JUMPIFNULL);
sqlite3ReleaseTempReg(pParse, r1);
}
pLevel->p1 = iIdxCur;
disableTerm(pLevel, pRangeStart);
disableTerm(pLevel, pRangeEnd);
+ }else if( pLevel->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 is constructed by creating a RowSet object
+ ** and populating it. Then looping over elements of the rowset.
+ **
+ ** Null 1
+ ** # fill RowSet 1 with entries where a=5 using i1
+ ** # fill Rowset 1 with entries where b=7 using i2
+ ** # fill Rowset 1 with entries where c=11 and d=13 i3 and t1
+ ** A: RowSetRead 1, B, 2
+ ** Seek i, 2
+ **
+ ** The bottom of the loop looks like this:
+ **
+ ** C: Goto 0, A
+ ** B:
+ */
}else{
- /* Case 4: There is no usable index. We must do a complete
+ /* Case 5: There is no usable index. We must do a complete
** scan of the entire table.
*/
assert( omitTable==0 );
projects / thirdparty / sqlite.git / commitdiff
