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chromium / chromium / src / 2b73527adf66a8d8d31b5061f72bda6cb6a08174 / . / third_party / sqlite / sqlite-src-3100200 / src / where.c
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/*
** 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"
#include "whereInt.h"
/* Forward declaration of methods */
static int whereLoopResize(sqlite3*, WhereLoop*, int);
/* Test variable that can be set to enable WHERE tracing */
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
/***/ int sqlite3WhereTrace = 0;
#endif
/*
** Return the estimated number of output rows from a WHERE clause
*/
u64 sqlite3WhereOutputRowCount(WhereInfo *pWInfo){
return sqlite3LogEstToInt(pWInfo->nRowOut);
}
/*
** Return one of the WHERE_DISTINCT_xxxxx values to indicate how this
** WHERE clause returns outputs for DISTINCT processing.
*/
int sqlite3WhereIsDistinct(WhereInfo *pWInfo){
return pWInfo->eDistinct;
}
/*
** Return TRUE if the WHERE clause returns rows in ORDER BY order.
** Return FALSE if the output needs to be sorted.
*/
int sqlite3WhereIsOrdered(WhereInfo *pWInfo){
return pWInfo->nOBSat;
}
/*
** Return the VDBE address or label to jump to in order to continue
** immediately with the next row of a WHERE clause.
*/
int sqlite3WhereContinueLabel(WhereInfo *pWInfo){
assert( pWInfo->iContinue!=0 );
return pWInfo->iContinue;
}
/*
** Return the VDBE address or label to jump to in order to break
** out of a WHERE loop.
*/
int sqlite3WhereBreakLabel(WhereInfo *pWInfo){
return pWInfo->iBreak;
}
/*
** Return ONEPASS_OFF (0) if an UPDATE or DELETE statement is unable to
** operate directly on the rowis returned by a WHERE clause. Return
** ONEPASS_SINGLE (1) if the statement can operation directly because only
** a single row is to be changed. Return ONEPASS_MULTI (2) if the one-pass
** optimization can be used on multiple
**
** If the ONEPASS optimization is used (if this routine returns true)
** then also write the indices of open cursors used by ONEPASS
** into aiCur[0] and aiCur[1]. iaCur[0] gets the cursor of the data
** table and iaCur[1] gets the cursor used by an auxiliary index.
** Either value may be -1, indicating that cursor is not used.
** Any cursors returned will have been opened for writing.
**
** aiCur[0] and aiCur[1] both get -1 if the where-clause logic is
** unable to use the ONEPASS optimization.
*/
int sqlite3WhereOkOnePass(WhereInfo *pWInfo, int *aiCur){
memcpy(aiCur, pWInfo->aiCurOnePass, sizeof(int)*2);
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace && pWInfo->eOnePass!=ONEPASS_OFF ){
sqlite3DebugPrintf("%s cursors: %d %d\n",
pWInfo->eOnePass==ONEPASS_SINGLE ? "ONEPASS_SINGLE" : "ONEPASS_MULTI",
aiCur[0], aiCur[1]);
}
#endif
return pWInfo->eOnePass;
}
/*
** Move the content of pSrc into pDest
*/
static void whereOrMove(WhereOrSet *pDest, WhereOrSet *pSrc){
pDest->n = pSrc->n;
memcpy(pDest->a, pSrc->a, pDest->n*sizeof(pDest->a[0]));
}
/*
** Try to insert a new prerequisite/cost entry into the WhereOrSet pSet.
**
** The new entry might overwrite an existing entry, or it might be
** appended, or it might be discarded. Do whatever is the right thing
** so that pSet keeps the N_OR_COST best entries seen so far.
*/
static int whereOrInsert(
WhereOrSet *pSet, /* The WhereOrSet to be updated */
Bitmask prereq, /* Prerequisites of the new entry */
LogEst rRun, /* Run-cost of the new entry */
LogEst nOut /* Number of outputs for the new entry */
){
u16 i;
WhereOrCost *p;
for(i=pSet->n, p=pSet->a; i>0; i--, p++){
if( rRun<=p->rRun && (prereq & p->prereq)==prereq ){
goto whereOrInsert_done;
}
if( p->rRun<=rRun && (p->prereq & prereq)==p->prereq ){
return 0;
}
}
if( pSet->n<N_OR_COST ){
p = &pSet->a[pSet->n++];
p->nOut = nOut;
}else{
p = pSet->a;
for(i=1; i<pSet->n; i++){
if( p->rRun>pSet->a[i].rRun ) p = pSet->a + i;
}
if( p->rRun<=rRun ) return 0;
}
whereOrInsert_done:
p->prereq = prereq;
p->rRun = rRun;
if( p->nOut>nOut ) p->nOut = nOut;
return 1;
}
/*
** Return the bitmask for the given cursor number. Return 0 if
** iCursor is not in the set.
*/
Bitmask sqlite3WhereGetMask(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 MASKBIT(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;
}
/*
** Advance to the next WhereTerm that matches according to the criteria
** established when the pScan object was initialized by whereScanInit().
** Return NULL if there are no more matching WhereTerms.
*/
static WhereTerm *whereScanNext(WhereScan *pScan){
int iCur; /* The cursor on the LHS of the term */
i16 iColumn; /* The column on the LHS of the term. -1 for IPK */
Expr *pX; /* An expression being tested */
WhereClause *pWC; /* Shorthand for pScan->pWC */
WhereTerm *pTerm; /* The term being tested */
int k = pScan->k; /* Where to start scanning */
while( pScan->iEquiv<=pScan->nEquiv ){
iCur = pScan->aiCur[pScan->iEquiv-1];
iColumn = pScan->aiColumn[pScan->iEquiv-1];
if( iColumn==XN_EXPR && pScan->pIdxExpr==0 ) return 0;
while( (pWC = pScan->pWC)!=0 ){
for(pTerm=pWC->a+k; k<pWC->nTerm; k++, pTerm++){
if( pTerm->leftCursor==iCur
&& pTerm->u.leftColumn==iColumn
&& (iColumn!=XN_EXPR
|| sqlite3ExprCompare(pTerm->pExpr->pLeft,pScan->pIdxExpr,iCur)==0)
&& (pScan->iEquiv<=1 || !ExprHasProperty(pTerm->pExpr, EP_FromJoin))
){
if( (pTerm->eOperator & WO_EQUIV)!=0
&& pScan->nEquiv<ArraySize(pScan->aiCur)
&& (pX = sqlite3ExprSkipCollate(pTerm->pExpr->pRight))->op==TK_COLUMN
){
int j;
for(j=0; j<pScan->nEquiv; j++){
if( pScan->aiCur[j]==pX->iTable
&& pScan->aiColumn[j]==pX->iColumn ){
break;
}
}
if( j==pScan->nEquiv ){
pScan->aiCur[j] = pX->iTable;
pScan->aiColumn[j] = pX->iColumn;
pScan->nEquiv++;
}
}
if( (pTerm->eOperator & pScan->opMask)!=0 ){
/* Verify the affinity and collating sequence match */
if( pScan->zCollName && (pTerm->eOperator & WO_ISNULL)==0 ){
CollSeq *pColl;
Parse *pParse = pWC->pWInfo->pParse;
pX = pTerm->pExpr;
if( !sqlite3IndexAffinityOk(pX, pScan->idxaff) ){
continue;
}
assert(pX->pLeft);
pColl = sqlite3BinaryCompareCollSeq(pParse,
pX->pLeft, pX->pRight);
if( pColl==0 ) pColl = pParse->db->pDfltColl;
if( sqlite3StrICmp(pColl->zName, pScan->zCollName) ){
continue;
}
}
if( (pTerm->eOperator & (WO_EQ|WO_IS))!=0
&& (pX = pTerm->pExpr->pRight)->op==TK_COLUMN
&& pX->iTable==pScan->aiCur[0]
&& pX->iColumn==pScan->aiColumn[0]
){
testcase( pTerm->eOperator & WO_IS );
continue;
}
pScan->k = k+1;
return pTerm;
}
}
}
pScan->pWC = pScan->pWC->pOuter;
k = 0;
}
pScan->pWC = pScan->pOrigWC;
k = 0;
pScan->iEquiv++;
}
return 0;
}
/*
** Initialize a WHERE clause scanner object. Return a pointer to the
** first match. Return NULL if there are no matches.
**
** The scanner will be searching the WHERE clause pWC. It will look
** for terms of the form "X <op> <expr>" where X is column iColumn of table
** iCur. The <op> must be one of the operators described by opMask.
**
** If the search is for X and the WHERE clause contains terms of the
** form X=Y then this routine might also return terms of the form
** "Y <op> <expr>". The number of levels of transitivity is limited,
** but is enough to handle most commonly occurring SQL statements.
**
** If X is not the INTEGER PRIMARY KEY then X must be compatible with
** index pIdx.
*/
static WhereTerm *whereScanInit(
WhereScan *pScan, /* The WhereScan object being initialized */
WhereClause *pWC, /* The WHERE clause to be scanned */
int iCur, /* Cursor to scan for */
int iColumn, /* Column to scan for */
u32 opMask, /* Operator(s) to scan for */
Index *pIdx /* Must be compatible with this index */
){
int j = 0;
/* memset(pScan, 0, sizeof(*pScan)); */
pScan->pOrigWC = pWC;
pScan->pWC = pWC;
pScan->pIdxExpr = 0;
if( pIdx ){
j = iColumn;
iColumn = pIdx->aiColumn[j];
if( iColumn==XN_EXPR ) pScan->pIdxExpr = pIdx->aColExpr->a[j].pExpr;
}
if( pIdx && iColumn>=0 ){
pScan->idxaff = pIdx->pTable->aCol[iColumn].affinity;
pScan->zCollName = pIdx->azColl[j];
}else{
pScan->idxaff = 0;
pScan->zCollName = 0;
}
pScan->opMask = opMask;
pScan->k = 0;
pScan->aiCur[0] = iCur;
pScan->aiColumn[0] = iColumn;
pScan->nEquiv = 1;
pScan->iEquiv = 1;
return whereScanNext(pScan);
}
/*
** 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.
**
** If pIdx!=0 then search for terms matching the iColumn-th column of pIdx
** rather than the iColumn-th column of table iCur.
**
** The term returned might by Y=<expr> if there is another constraint in
** the WHERE clause that specifies that X=Y. Any such constraints will be
** identified by the WO_EQUIV bit in the pTerm->eOperator field. The
** aiCur[]/iaColumn[] arrays hold X and all its equivalents. There are 11
** slots in aiCur[]/aiColumn[] so that means we can look for X plus up to 10
** other equivalent values. Hence a search for X will return <expr> if X=A1
** and A1=A2 and A2=A3 and ... and A9=A10 and A10=<expr>.
**
** If there are multiple terms in the WHERE clause of the form "X <op> <expr>"
** then try for the one with no dependencies on <expr> - in other words where
** <expr> is a constant expression of some kind. Only return entries of
** the form "X <op> Y" where Y is a column in another table if no terms of
** the form "X <op> <const-expr>" exist. If no terms with a constant RHS
** exist, try to return a term that does not use WO_EQUIV.
*/
WhereTerm *sqlite3WhereFindTerm(
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 *pResult = 0;
WhereTerm *p;
WhereScan scan;
p = whereScanInit(&scan, pWC, iCur, iColumn, op, pIdx);
op &= WO_EQ|WO_IS;
while( p ){
if( (p->prereqRight & notReady)==0 ){
if( p->prereqRight==0 && (p->eOperator&op)!=0 ){
testcase( p->eOperator & WO_IS );
return p;
}
if( pResult==0 ) pResult = p;
}
p = whereScanNext(&scan);
}
return pResult;
}
/*
** This function searches pList for an entry that matches the iCol-th column
** of index pIdx.
**
** If such an expression is found, its index in pList->a[] is returned. If
** no expression is found, -1 is returned.
*/
static int findIndexCol(
Parse *pParse, /* Parse context */
ExprList *pList, /* Expression list to search */
int iBase, /* Cursor for table associated with pIdx */
Index *pIdx, /* Index to match column of */
int iCol /* Column of index to match */
){
int i;
const char *zColl = pIdx->azColl[iCol];
for(i=0; i<pList->nExpr; i++){
Expr *p = sqlite3ExprSkipCollate(pList->a[i].pExpr);
if( p->op==TK_COLUMN
&& p->iColumn==pIdx->aiColumn[iCol]
&& p->iTable==iBase
){
CollSeq *pColl = sqlite3ExprCollSeq(pParse, pList->a[i].pExpr);
if( pColl && 0==sqlite3StrICmp(pColl->zName, zColl) ){
return i;
}
}
}
return -1;
}
/*
** Return TRUE if the iCol-th column of index pIdx is NOT NULL
*/
static int indexColumnNotNull(Index *pIdx, int iCol){
int j;
assert( pIdx!=0 );
assert( iCol>=0 && iCol<pIdx->nColumn );
j = pIdx->aiColumn[iCol];
if( j>=0 ){
return pIdx->pTable->aCol[j].notNull;
}else if( j==(-1) ){
return 1;
}else{
assert( j==(-2) );
return 0; /* Assume an indexed expression can always yield a NULL */
}
}
/*
** Return true if the DISTINCT expression-list passed as the third argument
** is redundant.
**
** A DISTINCT list is redundant if any subset of the columns in the
** DISTINCT list are collectively unique and individually non-null.
*/
static int isDistinctRedundant(
Parse *pParse, /* Parsing context */
SrcList *pTabList, /* The FROM clause */
WhereClause *pWC, /* The WHERE clause */
ExprList *pDistinct /* The result set that needs to be DISTINCT */
){
Table *pTab;
Index *pIdx;
int i;
int iBase;
/* If there is more than one table or sub-select in the FROM clause of
** this query, then it will not be possible to show that the DISTINCT
** clause is redundant. */
if( pTabList->nSrc!=1 ) return 0;
iBase = pTabList->a[0].iCursor;
pTab = pTabList->a[0].pTab;
/* If any of the expressions is an IPK column on table iBase, then return
** true. Note: The (p->iTable==iBase) part of this test may be false if the
** current SELECT is a correlated sub-query.
*/
for(i=0; i<pDistinct->nExpr; i++){
Expr *p = sqlite3ExprSkipCollate(pDistinct->a[i].pExpr);
if( p->op==TK_COLUMN && p->iTable==iBase && p->iColumn<0 ) return 1;
}
/* Loop through all indices on the table, checking each to see if it makes
** the DISTINCT qualifier redundant. It does so if:
**
** 1. The index is itself UNIQUE, and
**
** 2. All of the columns in the index are either part of the pDistinct
** list, or else the WHERE clause contains a term of the form "col=X",
** where X is a constant value. The collation sequences of the
** comparison and select-list expressions must match those of the index.
**
** 3. All of those index columns for which the WHERE clause does not
** contain a "col=X" term are subject to a NOT NULL constraint.
*/
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
if( !IsUniqueIndex(pIdx) ) continue;
for(i=0; i<pIdx->nKeyCol; i++){
if( 0==sqlite3WhereFindTerm(pWC, iBase, i, ~(Bitmask)0, WO_EQ, pIdx) ){
if( findIndexCol(pParse, pDistinct, iBase, pIdx, i)<0 ) break;
if( indexColumnNotNull(pIdx, i)==0 ) break;
}
}
if( i==pIdx->nKeyCol ){
/* This index implies that the DISTINCT qualifier is redundant. */
return 1;
}
}
return 0;
}
/*
** Estimate the logarithm of the input value to base 2.
*/
static LogEst estLog(LogEst N){
return N<=10 ? 0 : sqlite3LogEst(N) - 33;
}
/*
** Convert OP_Column opcodes to OP_Copy in previously generated code.
**
** This routine runs over generated VDBE code and translates OP_Column
** opcodes into OP_Copy when the table is being accessed via co-routine
** instead of via table lookup.
**
** If the bIncrRowid parameter is 0, then any OP_Rowid instructions on
** cursor iTabCur are transformed into OP_Null. Or, if bIncrRowid is non-zero,
** then each OP_Rowid is transformed into an instruction to increment the
** value stored in its output register.
*/
static void translateColumnToCopy(
Vdbe *v, /* The VDBE containing code to translate */
int iStart, /* Translate from this opcode to the end */
int iTabCur, /* OP_Column/OP_Rowid references to this table */
int iRegister, /* The first column is in this register */
int bIncrRowid /* If non-zero, transform OP_rowid to OP_AddImm(1) */
){
VdbeOp *pOp = sqlite3VdbeGetOp(v, iStart);
int iEnd = sqlite3VdbeCurrentAddr(v);
for(; iStart<iEnd; iStart++, pOp++){
if( pOp->p1!=iTabCur ) continue;
if( pOp->opcode==OP_Column ){
pOp->opcode = OP_Copy;
pOp->p1 = pOp->p2 + iRegister;
pOp->p2 = pOp->p3;
pOp->p3 = 0;
}else if( pOp->opcode==OP_Rowid ){
if( bIncrRowid ){
/* Increment the value stored in the P2 operand of the OP_Rowid. */
pOp->opcode = OP_AddImm;
pOp->p1 = pOp->p2;
pOp->p2 = 1;
}else{
pOp->opcode = OP_Null;
pOp->p1 = 0;
pOp->p3 = 0;
}
}
}
}
/*
** 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(WHERETRACE_ENABLED)
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);
sqlite3DebugPrintf(" estimatedRows=%lld\n", p->estimatedRows);
}
#else
#define TRACE_IDX_INPUTS(A)
#define TRACE_IDX_OUTPUTS(A)
#endif
#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|WO_IS))==0 ) return 0;
if( (pTerm->prereqRight & notReady)!=0 ) return 0;
if( pTerm->u.leftColumn<0 ) return 0;
aff = pSrc->pTab->aCol[pTerm->u.leftColumn].affinity;
if( !sqlite3IndexAffinityOk(pTerm->pExpr, aff) ) return 0;
testcase( pTerm->pExpr->op==TK_IS );
return 1;
}
#endif
#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 nKeyCol; /* Number of columns in the constructed index */
WhereTerm *pTerm; /* A single term of the WHERE clause */
WhereTerm *pWCEnd; /* End of pWC->a[] */
Index *pIdx; /* Object describing the transient index */
Vdbe *v; /* Prepared statement under construction */
int addrInit; /* Address of the initialization bypass jump */
Table *pTable; /* The table being indexed */
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 */
WhereLoop *pLoop; /* The Loop object */
char *zNotUsed; /* Extra space on the end of pIdx */
Bitmask idxCols; /* Bitmap of columns used for indexing */
Bitmask extraCols; /* Bitmap of additional columns */
u8 sentWarning = 0; /* True if a warnning has been issued */
Expr *pPartial = 0; /* Partial Index Expression */
int iContinue = 0; /* Jump here to skip excluded rows */
struct SrcList_item *pTabItem; /* FROM clause term being indexed */
int addrCounter = 0; /* Address where integer counter is initialized */
int regBase; /* Array of registers where record is assembled */
/* 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 );
addrInit = sqlite3CodeOnce(pParse); VdbeCoverage(v);
/* Count the number of columns that will be added to the index
** and used to match WHERE clause constraints */
nKeyCol = 0;
pTable = pSrc->pTab;
pWCEnd = &pWC->a[pWC->nTerm];
pLoop = pLevel->pWLoop;
idxCols = 0;
for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
Expr *pExpr = pTerm->pExpr;
assert( !ExprHasProperty(pExpr, EP_FromJoin) /* prereq always non-zero */
|| pExpr->iRightJoinTable!=pSrc->iCursor /* for the right-hand */
|| pLoop->prereq!=0 ); /* table of a LEFT JOIN */
if( pLoop->prereq==0
&& (pTerm->wtFlags & TERM_VIRTUAL)==0
&& !ExprHasProperty(pExpr, EP_FromJoin)
&& sqlite3ExprIsTableConstant(pExpr, pSrc->iCursor) ){
pPartial = sqlite3ExprAnd(pParse->db, pPartial,
sqlite3ExprDup(pParse->db, pExpr, 0));
}
if( termCanDriveIndex(pTerm, pSrc, notReady) ){
int iCol = pTerm->u.leftColumn;
Bitmask cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol);
testcase( iCol==BMS );
testcase( iCol==BMS-1 );
if( !sentWarning ){
sqlite3_log(SQLITE_WARNING_AUTOINDEX,
"automatic index on %s(%s)", pTable->zName,
pTable->aCol[iCol].zName);
sentWarning = 1;
}
if( (idxCols & cMask)==0 ){
if( whereLoopResize(pParse->db, pLoop, nKeyCol+1) ){
goto end_auto_index_create;
}
pLoop->aLTerm[nKeyCol++] = pTerm;
idxCols |= cMask;
}
}
}
assert( nKeyCol>0 );
pLoop->u.btree.nEq = pLoop->nLTerm = nKeyCol;
pLoop->wsFlags = WHERE_COLUMN_EQ | WHERE_IDX_ONLY | WHERE_INDEXED
| WHERE_AUTO_INDEX;
/* 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 | MASKBIT(BMS-1));
mxBitCol = MIN(BMS-1,pTable->nCol);
testcase( pTable->nCol==BMS-1 );
testcase( pTable->nCol==BMS-2 );
for(i=0; i<mxBitCol; i++){
if( extraCols & MASKBIT(i) ) nKeyCol++;
}
if( pSrc->colUsed & MASKBIT(BMS-1) ){
nKeyCol += pTable->nCol - BMS + 1;
}
/* Construct the Index object to describe this index */
pIdx = sqlite3AllocateIndexObject(pParse->db, nKeyCol+1, 0, &zNotUsed);
if( pIdx==0 ) goto end_auto_index_create;
pLoop->u.btree.pIndex = pIdx;
pIdx->zName = "auto-index";
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 ? MASKBIT(BMS-1) : MASKBIT(iCol);
testcase( iCol==BMS-1 );
testcase( iCol==BMS );
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] = pColl ? pColl->zName : sqlite3StrBINARY;
n++;
}
}
}
assert( (u32)n==pLoop->u.btree.nEq );
/* Add additional columns needed to make the automatic index into
** a covering index */
for(i=0; i<mxBitCol; i++){
if( extraCols & MASKBIT(i) ){
pIdx->aiColumn[n] = i;
pIdx->azColl[n] = sqlite3StrBINARY;
n++;
}
}
if( pSrc->colUsed & MASKBIT(BMS-1) ){
for(i=BMS-1; i<pTable->nCol; i++){
pIdx->aiColumn[n] = i;
pIdx->azColl[n] = sqlite3StrBINARY;
n++;
}
}
assert( n==nKeyCol );
pIdx->aiColumn[n] = XN_ROWID;
pIdx->azColl[n] = sqlite3StrBINARY;
/* Create the automatic index */
assert( pLevel->iIdxCur>=0 );
pLevel->iIdxCur = pParse->nTab++;
sqlite3VdbeAddOp2(v, OP_OpenAutoindex, pLevel->iIdxCur, nKeyCol+1);
sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
VdbeComment((v, "for %s", pTable->zName));
/* Fill the automatic index with content */
sqlite3ExprCachePush(pParse);
pTabItem = &pWC->pWInfo->pTabList->a[pLevel->iFrom];
if( pTabItem->fg.viaCoroutine ){
int regYield = pTabItem->regReturn;
addrCounter = sqlite3VdbeAddOp2(v, OP_Integer, 0, 0);
sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub);
addrTop = sqlite3VdbeAddOp1(v, OP_Yield, regYield);
VdbeCoverage(v);
VdbeComment((v, "next row of \"%s\"", pTabItem->pTab->zName));
}else{
addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, pLevel->iTabCur); VdbeCoverage(v);
}
if( pPartial ){
iContinue = sqlite3VdbeMakeLabel(v);
sqlite3ExprIfFalse(pParse, pPartial, iContinue, SQLITE_JUMPIFNULL);
pLoop->wsFlags |= WHERE_PARTIALIDX;
}
regRecord = sqlite3GetTempReg(pParse);
regBase = sqlite3GenerateIndexKey(
pParse, pIdx, pLevel->iTabCur, regRecord, 0, 0, 0, 0
);
sqlite3VdbeAddOp2(v, OP_IdxInsert, pLevel->iIdxCur, regRecord);
sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
if( pPartial ) sqlite3VdbeResolveLabel(v, iContinue);
if( pTabItem->fg.viaCoroutine ){
sqlite3VdbeChangeP2(v, addrCounter, regBase+n);
translateColumnToCopy(v, addrTop, pLevel->iTabCur, pTabItem->regResult, 1);
sqlite3VdbeGoto(v, addrTop);
pTabItem->fg.viaCoroutine = 0;
}else{
sqlite3VdbeAddOp2(v, OP_Next, pLevel->iTabCur, addrTop+1); VdbeCoverage(v);
}
sqlite3VdbeChangeP5(v, SQLITE_STMTSTATUS_AUTOINDEX);
sqlite3VdbeJumpHere(v, addrTop);
sqlite3ReleaseTempReg(pParse, regRecord);
sqlite3ExprCachePop(pParse);
/* Jump here when skipping the initialization */
sqlite3VdbeJumpHere(v, addrInit);
end_auto_index_create:
sqlite3ExprDelete(pParse->db, pPartial);
}
#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,
Bitmask mUnusable, /* Ignore terms with these prereqs */
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;
/* 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;
if( pTerm->prereqRight & mUnusable ) continue;
assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
testcase( pTerm->eOperator & WO_IN );
testcase( pTerm->eOperator & WO_ISNULL );
testcase( pTerm->eOperator & WO_IS );
testcase( pTerm->eOperator & WO_ALL );
if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV|WO_IS))==0 ) continue;
if( pTerm->wtFlags & TERM_VNULL ) continue;
assert( pTerm->u.leftColumn>=(-1) );
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 ){
int n = pOrderBy->nExpr;
for(i=0; i<n; i++){
Expr *pExpr = pOrderBy->a[i].pExpr;
if( pExpr->op!=TK_COLUMN || pExpr->iTable!=pSrc->iCursor ) break;
}
if( i==n){
nOrderBy = n;
}
}
/* 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");
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++){
u8 op;
if( pTerm->leftCursor != pSrc->iCursor ) continue;
if( pTerm->prereqRight & mUnusable ) continue;
assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
testcase( pTerm->eOperator & WO_IN );
testcase( pTerm->eOperator & WO_IS );
testcase( pTerm->eOperator & WO_ISNULL );
testcase( pTerm->eOperator & WO_ALL );
if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV|WO_IS))==0 ) continue;
if( pTerm->wtFlags & TERM_VNULL ) continue;
assert( pTerm->u.leftColumn>=(-1) );
pIdxCons[j].iColumn = pTerm->u.leftColumn;
pIdxCons[j].iTermOffset = i;
op = (u8)pTerm->eOperator & WO_ALL;
if( op==WO_IN ) op = WO_EQ;
if( op==WO_MATCH ){
op = pTerm->eMatchOp;
}
pIdxCons[j].op = op;
/* 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_IN|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 object that
** comes in as the 3rd argument to this function.
**
** 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;
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;
}
#endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) */
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
/*
** Estimate the location of a particular key among all keys in an
** index. Store the results in aStat as follows:
**
** aStat[0] Est. number of rows less than pRec
** aStat[1] Est. number of rows equal to pRec
**
** Return the index of the sample that is the smallest sample that
** is greater than or equal to pRec. Note that this index is not an index
** into the aSample[] array - it is an index into a virtual set of samples
** based on the contents of aSample[] and the number of fields in record
** pRec.
*/
static int whereKeyStats(
Parse *pParse, /* Database connection */
Index *pIdx, /* Index to consider domain of */
UnpackedRecord *pRec, /* Vector of values to consider */
int roundUp, /* Round up if true. Round down if false */
tRowcnt *aStat /* OUT: stats written here */
){
IndexSample *aSample = pIdx->aSample;
int iCol; /* Index of required stats in anEq[] etc. */
int i; /* Index of first sample >= pRec */
int iSample; /* Smallest sample larger than or equal to pRec */
int iMin = 0; /* Smallest sample not yet tested */
int iTest; /* Next sample to test */
int res; /* Result of comparison operation */
int nField; /* Number of fields in pRec */
tRowcnt iLower = 0; /* anLt[] + anEq[] of largest sample pRec is > */
#ifndef SQLITE_DEBUG
UNUSED_PARAMETER( pParse );
#endif
assert( pRec!=0 );
assert( pIdx->nSample>0 );
assert( pRec->nField>0 && pRec->nField<=pIdx->nSampleCol );
/* Do a binary search to find the first sample greater than or equal
** to pRec. If pRec contains a single field, the set of samples to search
** is simply the aSample[] array. If the samples in aSample[] contain more
** than one fields, all fields following the first are ignored.
**
** If pRec contains N fields, where N is more than one, then as well as the
** samples in aSample[] (truncated to N fields), the search also has to
** consider prefixes of those samples. For example, if the set of samples
** in aSample is:
**
** aSample[0] = (a, 5)
** aSample[1] = (a, 10)
** aSample[2] = (b, 5)
** aSample[3] = (c, 100)
** aSample[4] = (c, 105)
**
** Then the search space should ideally be the samples above and the
** unique prefixes [a], [b] and [c]. But since that is hard to organize,
** the code actually searches this set:
**
** 0: (a)
** 1: (a, 5)
** 2: (a, 10)
** 3: (a, 10)
** 4: (b)
** 5: (b, 5)
** 6: (c)
** 7: (c, 100)
** 8: (c, 105)
** 9: (c, 105)
**
** For each sample in the aSample[] array, N samples are present in the
** effective sample array. In the above, samples 0 and 1 are based on
** sample aSample[0]. Samples 2 and 3 on aSample[1] etc.
**
** Often, sample i of each block of N effective samples has (i+1) fields.
** Except, each sample may be extended to ensure that it is greater than or
** equal to the previous sample in the array. For example, in the above,
** sample 2 is the first sample of a block of N samples, so at first it
** appears that it should be 1 field in size. However, that would make it
** smaller than sample 1, so the binary search would not work. As a result,
** it is extended to two fields. The duplicates that this creates do not
** cause any problems.
*/
nField = pRec->nField;
iCol = 0;
iSample = pIdx->nSample * nField;
do{
int iSamp; /* Index in aSample[] of test sample */
int n; /* Number of fields in test sample */
iTest = (iMin+iSample)/2;
iSamp = iTest / nField;
if( iSamp>0 ){
/* The proposed effective sample is a prefix of sample aSample[iSamp].
** Specifically, the shortest prefix of at least (1 + iTest%nField)
** fields that is greater than the previous effective sample. */
for(n=(iTest % nField) + 1; n<nField; n++){
if( aSample[iSamp-1].anLt[n-1]!=aSample[iSamp].anLt[n-1] ) break;
}
}else{
n = iTest + 1;
}
pRec->nField = n;
res = sqlite3VdbeRecordCompare(aSample[iSamp].n, aSample[iSamp].p, pRec);
if( res<0 ){
iLower = aSample[iSamp].anLt[n-1] + aSample[iSamp].anEq[n-1];
iMin = iTest+1;
}else if( res==0 && n<nField ){
iLower = aSample[iSamp].anLt[n-1];
iMin = iTest+1;
res = -1;
}else{
iSample = iTest;
iCol = n-1;
}
}while( res && iMin<iSample );
i = iSample / nField;
#ifdef SQLITE_DEBUG
/* The following assert statements check that the binary search code
** above found the right answer. This block serves no purpose other
** than to invoke the asserts. */
if( pParse->db->mallocFailed==0 ){
if( res==0 ){
/* If (res==0) is true, then pRec must be equal to sample i. */
assert( i<pIdx->nSample );
assert( iCol==nField-1 );
pRec->nField = nField;
assert( 0==sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)
|| pParse->db->mallocFailed
);
}else{
/* Unless i==pIdx->nSample, indicating that pRec is larger than
** all samples in the aSample[] array, pRec must be smaller than the
** (iCol+1) field prefix of sample i. */
assert( i<=pIdx->nSample && i>=0 );
pRec->nField = iCol+1;
assert( i==pIdx->nSample
|| sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)>0
|| pParse->db->mallocFailed );
/* if i==0 and iCol==0, then record pRec is smaller than all samples
** in the aSample[] array. Otherwise, if (iCol>0) then pRec must
** be greater than or equal to the (iCol) field prefix of sample i.
** If (i>0), then pRec must also be greater than sample (i-1). */
if( iCol>0 ){
pRec->nField = iCol;
assert( sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)<=0
|| pParse->db->mallocFailed );
}
if( i>0 ){
pRec->nField = nField;
assert( sqlite3VdbeRecordCompare(aSample[i-1].n, aSample[i-1].p, pRec)<0
|| pParse->db->mallocFailed );
}
}
}
#endif /* ifdef SQLITE_DEBUG */
if( res==0 ){
/* Record pRec is equal to sample i */
assert( iCol==nField-1 );
aStat[0] = aSample[i].anLt[iCol];
aStat[1] = aSample[i].anEq[iCol];
}else{
/* At this point, the (iCol+1) field prefix of aSample[i] is the first
** sample that is greater than pRec. Or, if i==pIdx->nSample then pRec
** is larger than all samples in the array. */
tRowcnt iUpper, iGap;
if( i>=pIdx->nSample ){
iUpper = sqlite3LogEstToInt(pIdx->aiRowLogEst[0]);
}else{
iUpper = aSample[i].anLt[iCol];
}
if( iLower>=iUpper ){
iGap = 0;
}else{
iGap = iUpper - iLower;
}
if( roundUp ){
iGap = (iGap*2)/3;
}else{
iGap = iGap/3;
}
aStat[0] = iLower + iGap;
aStat[1] = pIdx->aAvgEq[iCol];
}
/* Restore the pRec->nField value before returning. */
pRec->nField = nField;
return i;
}
#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
/*
** If it is not NULL, pTerm is a term that provides an upper or lower
** bound on a range scan. Without considering pTerm, it is estimated
** that the scan will visit nNew rows. This function returns the number
** estimated to be visited after taking pTerm into account.
**
** If the user explicitly specified a likelihood() value for this term,
** then the return value is the likelihood multiplied by the number of
** input rows. Otherwise, this function assumes that an "IS NOT NULL" term
** has a likelihood of 0.50, and any other term a likelihood of 0.25.
*/
static LogEst whereRangeAdjust(WhereTerm *pTerm, LogEst nNew){
LogEst nRet = nNew;
if( pTerm ){
if( pTerm->truthProb<=0 ){
nRet += pTerm->truthProb;
}else if( (pTerm->wtFlags & TERM_VNULL)==0 ){
nRet -= 20; assert( 20==sqlite3LogEst(4) );
}
}
return nRet;
}
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
/*
** Return the affinity for a single column of an index.
*/
static char sqlite3IndexColumnAffinity(sqlite3 *db, Index *pIdx, int iCol){
assert( iCol>=0 && iCol<pIdx->nColumn );
if( !pIdx->zColAff ){
if( sqlite3IndexAffinityStr(db, pIdx)==0 ) return SQLITE_AFF_BLOB;
}
return pIdx->zColAff[iCol];
}
#endif
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
/*
** This function is called to estimate the number of rows visited by a
** range-scan on a skip-scan index. For example:
**
** CREATE INDEX i1 ON t1(a, b, c);
** SELECT * FROM t1 WHERE a=? AND c BETWEEN ? AND ?;
**
** Value pLoop->nOut is currently set to the estimated number of rows
** visited for scanning (a=? AND b=?). This function reduces that estimate
** by some factor to account for the (c BETWEEN ? AND ?) expression based
** on the stat4 data for the index. this scan will be peformed multiple
** times (once for each (a,b) combination that matches a=?) is dealt with
** by the caller.
**
** It does this by scanning through all stat4 samples, comparing values
** extracted from pLower and pUpper with the corresponding column in each
** sample. If L and U are the number of samples found to be less than or
** equal to the values extracted from pLower and pUpper respectively, and
** N is the total number of samples, the pLoop->nOut value is adjusted
** as follows:
**
** nOut = nOut * ( min(U - L, 1) / N )
**
** If pLower is NULL, or a value cannot be extracted from the term, L is
** set to zero. If pUpper is NULL, or a value cannot be extracted from it,
** U is set to N.
**
** Normally, this function sets *pbDone to 1 before returning. However,
** if no value can be extracted from either pLower or pUpper (and so the
** estimate of the number of rows delivered remains unchanged), *pbDone
** is left as is.
**
** If an error occurs, an SQLite error code is returned. Otherwise,
** SQLITE_OK.
*/
static int whereRangeSkipScanEst(
Parse *pParse, /* Parsing & code generating context */
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 */
WhereLoop *pLoop, /* Update the .nOut value of this loop */
int *pbDone /* Set to true if at least one expr. value extracted */
){
Index *p = pLoop->u.btree.pIndex;
int nEq = pLoop->u.btree.nEq;
sqlite3 *db = pParse->db;
int nLower = -1;
int nUpper = p->nSample+1;
int rc = SQLITE_OK;
u8 aff = sqlite3IndexColumnAffinity(db, p, nEq);
CollSeq *pColl;
sqlite3_value *p1 = 0; /* Value extracted from pLower */
sqlite3_value *p2 = 0; /* Value extracted from pUpper */
sqlite3_value *pVal = 0; /* Value extracted from record */
pColl = sqlite3LocateCollSeq(pParse, p->azColl[nEq]);
if( pLower ){
rc = sqlite3Stat4ValueFromExpr(pParse, pLower->pExpr->pRight, aff, &p1);
nLower = 0;
}
if( pUpper && rc==SQLITE_OK ){
rc = sqlite3Stat4ValueFromExpr(pParse, pUpper->pExpr->pRight, aff, &p2);
nUpper = p2 ? 0 : p->nSample;
}
if( p1 || p2 ){
int i;
int nDiff;
for(i=0; rc==SQLITE_OK && i<p->nSample; i++){
rc = sqlite3Stat4Column(db, p->aSample[i].p, p->aSample[i].n, nEq, &pVal);
if( rc==SQLITE_OK && p1 ){
int res = sqlite3MemCompare(p1, pVal, pColl);
if( res>=0 ) nLower++;
}
if( rc==SQLITE_OK && p2 ){
int res = sqlite3MemCompare(p2, pVal, pColl);
if( res>=0 ) nUpper++;
}
}
nDiff = (nUpper - nLower);
if( nDiff<=0 ) nDiff = 1;
/* If there is both an upper and lower bound specified, and the
** comparisons indicate that they are close together, use the fallback
** method (assume that the scan visits 1/64 of the rows) for estimating
** the number of rows visited. Otherwise, estimate the number of rows
** using the method described in the header comment for this function. */
if( nDiff!=1 || pUpper==0 || pLower==0 ){
int nAdjust = (sqlite3LogEst(p->nSample) - sqlite3LogEst(nDiff));
pLoop->nOut -= nAdjust;
*pbDone = 1;
WHERETRACE(0x10, ("range skip-scan regions: %u..%u adjust=%d est=%d\n",
nLower, nUpper, nAdjust*-1, pLoop->nOut));
}
}else{
assert( *pbDone==0 );
}
sqlite3ValueFree(p1);
sqlite3ValueFree(p2);
sqlite3ValueFree(pVal);
return rc;
}
#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
/*
** 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 value in (pBuilder->pNew->u.btree.nEq) is the number 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 is set to 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 is set to 0.
**
** When this function is called, *pnOut is set to the sqlite3LogEst() of the
** number of rows that the index scan is expected to visit without
** considering the range constraints. If nEq is 0, then *pnOut is the number of
** rows in the index. Assuming no error occurs, *pnOut is adjusted (reduced)
** to account for the range constraints pLower and pUpper.
**
** In the absence of sqlite_stat4 ANALYZE data, or if such data cannot be
** used, a single range inequality reduces the search space by a factor of 4.
** and a pair of constraints (x>? AND x<?) reduces the expected number of
** rows visited by a factor of 64.
*/
static int whereRangeScanEst(
Parse *pParse, /* Parsing & code generating context */
WhereLoopBuilder *pBuilder,
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 */
WhereLoop *pLoop /* Modify the .nOut and maybe .rRun fields */
){
int rc = SQLITE_OK;
int nOut = pLoop->nOut;
LogEst nNew;
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
Index *p = pLoop->u.btree.pIndex;
int nEq = pLoop->u.btree.nEq;
if( p->nSample>0 && nEq<p->nSampleCol ){
if( nEq==pBuilder->nRecValid ){
UnpackedRecord *pRec = pBuilder->pRec;
tRowcnt a[2];
u8 aff;
/* Variable iLower will be set to the estimate of the number of rows in
** the index that are less than the lower bound of the range query. The
** lower bound being the concatenation of $P and $L, where $P is the
** key-prefix formed by the nEq values matched against the nEq left-most
** columns of the index, and $L is the value in pLower.
**
** Or, if pLower is NULL or $L cannot be extracted from it (because it
** is not a simple variable or literal value), the lower bound of the
** range is $P. Due to a quirk in the way whereKeyStats() works, even
** if $L is available, whereKeyStats() is called for both ($P) and
** ($P:$L) and the larger of the two returned values is used.
**
** Similarly, iUpper is to be set to the estimate of the number of rows
** less than the upper bound of the range query. Where the upper bound
** is either ($P) or ($P:$U). Again, even if $U is available, both values
** of iUpper are requested of whereKeyStats() and the smaller used.
**
** The number of rows between the two bounds is then just iUpper-iLower.
*/
tRowcnt iLower; /* Rows less than the lower bound */
tRowcnt iUpper; /* Rows less than the upper bound */
int iLwrIdx = -2; /* aSample[] for the lower bound */
int iUprIdx = -1; /* aSample[] for the upper bound */
if( pRec ){
testcase( pRec->nField!=pBuilder->nRecValid );
pRec->nField = pBuilder->nRecValid;
}
aff = sqlite3IndexColumnAffinity(pParse->db, p, nEq);
assert( nEq!=p->nKeyCol || aff==SQLITE_AFF_INTEGER );
/* Determine iLower and iUpper using ($P) only. */
if( nEq==0 ){
iLower = 0;
iUpper = p->nRowEst0;
}else{
/* Note: this call could be optimized away - since the same values must
** have been requested when testing key $P in whereEqualScanEst(). */
whereKeyStats(pParse, p, pRec, 0, a);
iLower = a[0];
iUpper = a[0] + a[1];
}
assert( pLower==0 || (pLower->eOperator & (WO_GT|WO_GE))!=0 );
assert( pUpper==0 || (pUpper->eOperator & (WO_LT|WO_LE))!=0 );
assert( p->aSortOrder!=0 );
if( p->aSortOrder[nEq] ){
/* The roles of pLower and pUpper are swapped for a DESC index */
SWAP(WhereTerm*, pLower, pUpper);
}
/* If possible, improve on the iLower estimate using ($P:$L). */
if( pLower ){
int bOk; /* True if value is extracted from pExpr */
Expr *pExpr = pLower->pExpr->pRight;
rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
if( rc==SQLITE_OK && bOk ){
tRowcnt iNew;
iLwrIdx = whereKeyStats(pParse, p, pRec, 0, a);
iNew = a[0] + ((pLower->eOperator & (WO_GT|WO_LE)) ? a[1] : 0);
if( iNew>iLower ) iLower = iNew;
nOut--;
pLower = 0;
}
}
/* If possible, improve on the iUpper estimate using ($P:$U). */
if( pUpper ){
int bOk; /* True if value is extracted from pExpr */
Expr *pExpr = pUpper->pExpr->pRight;
rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
if( rc==SQLITE_OK && bOk ){
tRowcnt iNew;
iUprIdx = whereKeyStats(pParse, p, pRec, 1, a);
iNew = a[0] + ((pUpper->eOperator & (WO_GT|WO_LE)) ? a[1] : 0);
if( iNew<iUpper ) iUpper = iNew;
nOut--;
pUpper = 0;
}
}
pBuilder->pRec = pRec;
if( rc==SQLITE_OK ){
if( iUpper>iLower ){
nNew = sqlite3LogEst(iUpper - iLower);
/* TUNING: If both iUpper and iLower are derived from the same
** sample, then assume they are 4x more selective. This brings
** the estimated selectivity more in line with what it would be
** if estimated without the use of STAT3/4 tables. */
if( iLwrIdx==iUprIdx ) nNew -= 20; assert( 20==sqlite3LogEst(4) );
}else{
nNew = 10; assert( 10==sqlite3LogEst(2) );
}
if( nNew<nOut ){
nOut = nNew;
}
WHERETRACE(0x10, ("STAT4 range scan: %u..%u est=%d\n",
(u32)iLower, (u32)iUpper, nOut));
}
}else{
int bDone = 0;
rc = whereRangeSkipScanEst(pParse, pLower, pUpper, pLoop, &bDone);
if( bDone ) return rc;
}
}
#else
UNUSED_PARAMETER(pParse);
UNUSED_PARAMETER(pBuilder);
assert( pLower || pUpper );
#endif
assert( pUpper==0 || (pUpper->wtFlags & TERM_VNULL)==0 );
nNew = whereRangeAdjust(pLower, nOut);
nNew = whereRangeAdjust(pUpper, nNew);
/* TUNING: If there is both an upper and lower limit and neither limit
** has an application-defined likelihood(), assume the range is
** reduced by an additional 75%. This means that, by default, an open-ended
** range query (e.g. col > ?) is assumed to match 1/4 of the rows in the
** index. While a closed range (e.g. col BETWEEN ? AND ?) is estimated to
** match 1/64 of the index. */
if( pLower && pLower->truthProb>0 && pUpper && pUpper->truthProb>0 ){
nNew -= 20;
}
nOut -= (pLower!=0) + (pUpper!=0);
if( nNew<10 ) nNew = 10;
if( nNew<nOut ) nOut = nNew;
#if defined(WHERETRACE_ENABLED)
if( pLoop->nOut>nOut ){
WHERETRACE(0x10,("Range scan lowers nOut from %d to %d\n",
pLoop->nOut, nOut));
}
#endif
pLoop->nOut = (LogEst)nOut;
return rc;
}
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
/*
** 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_stat3 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 */
WhereLoopBuilder *pBuilder,
Expr *pExpr, /* Expression for VALUE in the x=VALUE constraint */
tRowcnt *pnRow /* Write the revised row estimate here */
){
Index *p = pBuilder->pNew->u.btree.pIndex;
int nEq = pBuilder->pNew->u.btree.nEq;
UnpackedRecord *pRec = pBuilder->pRec;
u8 aff; /* Column affinity */
int rc; /* Subfunction return code */
tRowcnt a[2]; /* Statistics */
int bOk;
assert( nEq>=1 );
assert( nEq<=p->nColumn );
assert( p->aSample!=0 );
assert( p->nSample>0 );
assert( pBuilder->nRecValid<nEq );
/* If values are not available for all fields of the index to the left
** of this one, no estimate can be made. Return SQLITE_NOTFOUND. */
if( pBuilder->nRecValid<(nEq-1) ){
return SQLITE_NOTFOUND;
}
/* This is an optimization only. The call to sqlite3Stat4ProbeSetValue()
** below would return the same value. */
if( nEq>=p->nColumn ){
*pnRow = 1;
return SQLITE_OK;
}
aff = sqlite3IndexColumnAffinity(pParse->db, p, nEq-1);
rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq-1, &bOk);
pBuilder->pRec = pRec;
if( rc!=SQLITE_OK ) return rc;
if( bOk==0 ) return SQLITE_NOTFOUND;
pBuilder->nRecValid = nEq;
whereKeyStats(pParse, p, pRec, 0, a);
WHERETRACE(0x10,("equality scan regions: %d\n", (int)a[1]));
*pnRow = a[1];
return rc;
}
#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
/*
** 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 */
WhereLoopBuilder *pBuilder,
ExprList *pList, /* The value list on the RHS of "x IN (v1,v2,v3,...)" */
tRowcnt *pnRow /* Write the revised row estimate here */
){
Index *p = pBuilder->pNew->u.btree.pIndex;
i64 nRow0 = sqlite3LogEstToInt(p->aiRowLogEst[0]);
int nRecValid = pBuilder->nRecValid;
int rc = SQLITE_OK; /* Subfunction return code */
tRowcnt nEst; /* Number of rows for a single term */
tRowcnt nRowEst = 0; /* New estimate of the number of rows */
int i; /* Loop counter */
assert( p->aSample!=0 );
for(i=0; rc==SQLITE_OK && i<pList->nExpr; i++){
nEst = nRow0;
rc = whereEqualScanEst(pParse, pBuilder, pList->a[i].pExpr, &nEst);
nRowEst += nEst;
pBuilder->nRecValid = nRecValid;
}
if( rc==SQLITE_OK ){
if( nRowEst > nRow0 ) nRowEst = nRow0;
*pnRow = nRowEst;
WHERETRACE(0x10,("IN row estimate: est=%d\n", nRowEst));
}
assert( pBuilder->nRecValid==nRecValid );
return rc;
}
#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
#ifdef WHERETRACE_ENABLED
/*
** Print the content of a WhereTerm object
*/
static void whereTermPrint(WhereTerm *pTerm, int iTerm){
if( pTerm==0 ){
sqlite3DebugPrintf("TERM-%-3d NULL\n", iTerm);
}else{
char zType[4];
memcpy(zType, "...", 4);
if( pTerm->wtFlags & TERM_VIRTUAL ) zType[0] = 'V';
if( pTerm->eOperator & WO_EQUIV ) zType[1] = 'E';
if( ExprHasProperty(pTerm->pExpr, EP_FromJoin) ) zType[2] = 'L';
sqlite3DebugPrintf(
"TERM-%-3d %p %s cursor=%-3d prob=%-3d op=0x%03x wtFlags=0x%04x\n",
iTerm, pTerm, zType, pTerm->leftCursor, pTerm->truthProb,
pTerm->eOperator, pTerm->wtFlags);
sqlite3TreeViewExpr(0, pTerm->pExpr, 0);
}
}
#endif
#ifdef WHERETRACE_ENABLED
/*
** Print a WhereLoop object for debugging purposes
*/
static void whereLoopPrint(WhereLoop *p, WhereClause *pWC){
WhereInfo *pWInfo = pWC->pWInfo;
int nb = 1+(pWInfo->pTabList->nSrc+7)/8;
struct SrcList_item *pItem = pWInfo->pTabList->a + p->iTab;
Table *pTab = pItem->pTab;
sqlite3DebugPrintf("%c%2d.%0*llx.%0*llx", p->cId,
p->iTab, nb, p->maskSelf, nb, p->prereq);
sqlite3DebugPrintf(" %12s",
pItem->zAlias ? pItem->zAlias : pTab->zName);
if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){
const char *zName;
if( p->u.btree.pIndex && (zName = p->u.btree.pIndex->zName)!=0 ){
if( strncmp(zName, "sqlite_autoindex_", 17)==0 ){
int i = sqlite3Strlen30(zName) - 1;
while( zName[i]!='_' ) i--;
zName += i;
}
sqlite3DebugPrintf(".%-16s %2d", zName, p->u.btree.nEq);
}else{
sqlite3DebugPrintf("%20s","");
}
}else{
char *z;
if( p->u.vtab.idxStr ){
z = sqlite3_mprintf("(%d,\"%s\",%x)",
p->u.vtab.idxNum, p->u.vtab.idxStr, p->u.vtab.omitMask);
}else{
z = sqlite3_mprintf("(%d,%x)", p->u.vtab.idxNum, p->u.vtab.omitMask);
}
sqlite3DebugPrintf(" %-19s", z);
sqlite3_free(z);
}
if( p->wsFlags & WHERE_SKIPSCAN ){
sqlite3DebugPrintf(" f %05x %d-%d", p->wsFlags, p->nLTerm,p->nSkip);
}else{
sqlite3DebugPrintf(" f %05x N %d", p->wsFlags, p->nLTerm);
}
sqlite3DebugPrintf(" cost %d,%d,%d\n", p->rSetup, p->rRun, p->nOut);
if( p->nLTerm && (sqlite3WhereTrace & 0x100)!=0 ){
int i;
for(i=0; i<p->nLTerm; i++){
whereTermPrint(p->aLTerm[i], i);
}
}
}
#endif
/*
** Convert bulk memory into a valid WhereLoop that can be passed
** to whereLoopClear harmlessly.
*/
static void whereLoopInit(WhereLoop *p){
p->aLTerm = p->aLTermSpace;
p->nLTerm = 0;
p->nLSlot = ArraySize(p->aLTermSpace);
p->wsFlags = 0;
}
/*
** Clear the WhereLoop.u union. Leave WhereLoop.pLTerm intact.
*/
static void whereLoopClearUnion(sqlite3 *db, WhereLoop *p){
if( p->wsFlags & (WHERE_VIRTUALTABLE|WHERE_AUTO_INDEX) ){
if( (p->wsFlags & WHERE_VIRTUALTABLE)!=0 && p->u.vtab.needFree ){
sqlite3_free(p->u.vtab.idxStr);
p->u.vtab.needFree = 0;
p->u.vtab.idxStr = 0;
}else if( (p->wsFlags & WHERE_AUTO_INDEX)!=0 && p->u.btree.pIndex!=0 ){
sqlite3DbFree(db, p->u.btree.pIndex->zColAff);
sqlite3DbFree(db, p->u.btree.pIndex);
p->u.btree.pIndex = 0;
}
}
}
/*
** Deallocate internal memory used by a WhereLoop object
*/
static void whereLoopClear(sqlite3 *db, WhereLoop *p){
if( p->aLTerm!=p->aLTermSpace ) sqlite3DbFree(db, p->aLTerm);
whereLoopClearUnion(db, p);
whereLoopInit(p);
}
/*
** Increase the memory allocation for pLoop->aLTerm[] to be at least n.
*/
static int whereLoopResize(sqlite3 *db, WhereLoop *p, int n){
WhereTerm **paNew;
if( p->nLSlot>=n ) return SQLITE_OK;
n = (n+7)&~7;
paNew = sqlite3DbMallocRaw(db, sizeof(p->aLTerm[0])*n);
if( paNew==0 ) return SQLITE_NOMEM;
memcpy(paNew, p->aLTerm, sizeof(p->aLTerm[0])*p->nLSlot);
if( p->aLTerm!=p->aLTermSpace ) sqlite3DbFree(db, p->aLTerm);
p->aLTerm = paNew;
p->nLSlot = n;
return SQLITE_OK;
}
/*
** Transfer content from the second pLoop into the first.
*/
static int whereLoopXfer(sqlite3 *db, WhereLoop *pTo, WhereLoop *pFrom){
whereLoopClearUnion(db, pTo);
if( whereLoopResize(db, pTo, pFrom->nLTerm) ){
memset(&pTo->u, 0, sizeof(pTo->u));
return SQLITE_NOMEM;
}
memcpy(pTo, pFrom, WHERE_LOOP_XFER_SZ);
memcpy(pTo->aLTerm, pFrom->aLTerm, pTo->nLTerm*sizeof(pTo->aLTerm[0]));
if( pFrom->wsFlags & WHERE_VIRTUALTABLE ){
pFrom->u.vtab.needFree = 0;
}else if( (pFrom->wsFlags & WHERE_AUTO_INDEX)!=0 ){
pFrom->u.btree.pIndex = 0;
}
return SQLITE_OK;
}
/*
** Delete a WhereLoop object
*/
static void whereLoopDelete(sqlite3 *db, WhereLoop *p){
whereLoopClear(db, p);
sqlite3DbFree(db, p);
}
/*
** Free a WhereInfo structure
*/
static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
if( ALWAYS(pWInfo) ){
int i;
for(i=0; i<pWInfo->nLevel; i++){
WhereLevel *pLevel = &pWInfo->a[i];
if( pLevel->pWLoop && (pLevel->pWLoop->wsFlags & WHERE_IN_ABLE) ){
sqlite3DbFree(db, pLevel->u.in.aInLoop);
}
}
sqlite3WhereClauseClear(&pWInfo->sWC);
while( pWInfo->pLoops ){
WhereLoop *p = pWInfo->pLoops;
pWInfo->pLoops = p->pNextLoop;
whereLoopDelete(db, p);
}
sqlite3DbFree(db, pWInfo);
}
}
/*
** Return TRUE if all of the following are true:
**
** (1) X has the same or lower cost that Y
** (2) X is a proper subset of Y
** (3) X skips at least as many columns as Y
**
** By "proper subset" we mean that X uses fewer WHERE clause terms
** than Y and that every WHERE clause term used by X is also used
** by Y.
**
** If X is a proper subset of Y then Y is a better choice and ought
** to have a lower cost. This routine returns TRUE when that cost
** relationship is inverted and needs to be adjusted. The third rule
** was added because if X uses skip-scan less than Y it still might
** deserve a lower cost even if it is a proper subset of Y.
*/
static int whereLoopCheaperProperSubset(
const WhereLoop *pX, /* First WhereLoop to compare */
const WhereLoop *pY /* Compare against this WhereLoop */
){
int i, j;
if( pX->nLTerm-pX->nSkip >= pY->nLTerm-pY->nSkip ){
return 0; /* X is not a subset of Y */
}
if( pY->nSkip > pX->nSkip ) return 0;
if( pX->rRun >= pY->rRun ){
if( pX->rRun > pY->rRun ) return 0; /* X costs more than Y */
if( pX->nOut > pY->nOut ) return 0; /* X costs more than Y */
}
for(i=pX->nLTerm-1; i>=0; i--){
if( pX->aLTerm[i]==0 ) continue;
for(j=pY->nLTerm-1; j>=0; j--){
if( pY->aLTerm[j]==pX->aLTerm[i] ) break;
}
if( j<0 ) return 0; /* X not a subset of Y since term X[i] not used by Y */
}
return 1; /* All conditions meet */
}
/*
** Try to adjust the cost of WhereLoop pTemplate upwards or downwards so
** that:
**
** (1) pTemplate costs less than any other WhereLoops that are a proper
** subset of pTemplate
**
** (2) pTemplate costs more than any other WhereLoops for which pTemplate
** is a proper subset.
**
** To say "WhereLoop X is a proper subset of Y" means that X uses fewer
** WHERE clause terms than Y and that every WHERE clause term used by X is
** also used by Y.
*/
static void whereLoopAdjustCost(const WhereLoop *p, WhereLoop *pTemplate){
if( (pTemplate->wsFlags & WHERE_INDEXED)==0 ) return;
for(; p; p=p->pNextLoop){
if( p->iTab!=pTemplate->iTab ) continue;
if( (p->wsFlags & WHERE_INDEXED)==0 ) continue;
if( whereLoopCheaperProperSubset(p, pTemplate) ){
/* Adjust pTemplate cost downward so that it is cheaper than its
** subset p. */
WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n",
pTemplate->rRun, pTemplate->nOut, p->rRun, p->nOut-1));
pTemplate->rRun = p->rRun;
pTemplate->nOut = p->nOut - 1;
}else if( whereLoopCheaperProperSubset(pTemplate, p) ){
/* Adjust pTemplate cost upward so that it is costlier than p since
** pTemplate is a proper subset of p */
WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n",
pTemplate->rRun, pTemplate->nOut, p->rRun, p->nOut+1));
pTemplate->rRun = p->rRun;
pTemplate->nOut = p->nOut + 1;
}
}
}
/*
** Search the list of WhereLoops in *ppPrev looking for one that can be
** supplanted by pTemplate.
**
** Return NULL if the WhereLoop list contains an entry that can supplant
** pTemplate, in other words if pTemplate does not belong on the list.
**
** If pX is a WhereLoop that pTemplate can supplant, then return the
** link that points to pX.
**
** If pTemplate cannot supplant any existing element of the list but needs
** to be added to the list, then return a pointer to the tail of the list.
*/
static WhereLoop **whereLoopFindLesser(
WhereLoop **ppPrev,
const WhereLoop *pTemplate
){
WhereLoop *p;
for(p=(*ppPrev); p; ppPrev=&p->pNextLoop, p=*ppPrev){
if( p->iTab!=pTemplate->iTab || p->iSortIdx!=pTemplate->iSortIdx ){
/* If either the iTab or iSortIdx values for two WhereLoop are different
** then those WhereLoops need to be considered separately. Neither is
** a candidate to replace the other. */
continue;
}
/* In the current implementation, the rSetup value is either zero
** or the cost of building an automatic index (NlogN) and the NlogN
** is the same for compatible WhereLoops. */
assert( p->rSetup==0 || pTemplate->rSetup==0
|| p->rSetup==pTemplate->rSetup );
/* whereLoopAddBtree() always generates and inserts the automatic index
** case first. Hence compatible candidate WhereLoops never have a larger
** rSetup. Call this SETUP-INVARIANT */
assert( p->rSetup>=pTemplate->rSetup );
/* Any loop using an appliation-defined index (or PRIMARY KEY or
** UNIQUE constraint) with one or more == constraints is better
** than an automatic index. Unless it is a skip-scan. */
if( (p->wsFlags & WHERE_AUTO_INDEX)!=0
&& (pTemplate->nSkip)==0
&& (pTemplate->wsFlags & WHERE_INDEXED)!=0
&& (pTemplate->wsFlags & WHERE_COLUMN_EQ)!=0
&& (p->prereq & pTemplate->prereq)==pTemplate->prereq
){
break;
}
/* If existing WhereLoop p is better than pTemplate, pTemplate can be
** discarded. WhereLoop p is better if:
** (1) p has no more dependencies than pTemplate, and
** (2) p has an equal or lower cost than pTemplate
*/
if( (p->prereq & pTemplate->prereq)==p->prereq /* (1) */
&& p->rSetup<=pTemplate->rSetup /* (2a) */
&& p->rRun<=pTemplate->rRun /* (2b) */
&& p->nOut<=pTemplate->nOut /* (2c) */
){
return 0; /* Discard pTemplate */
}
/* If pTemplate is always better than p, then cause p to be overwritten
** with pTemplate. pTemplate is better than p if:
** (1) pTemplate has no more dependences than p, and
** (2) pTemplate has an equal or lower cost than p.
*/
if( (p->prereq & pTemplate->prereq)==pTemplate->prereq /* (1) */
&& p->rRun>=pTemplate->rRun /* (2a) */
&& p->nOut>=pTemplate->nOut /* (2b) */
){
assert( p->rSetup>=pTemplate->rSetup ); /* SETUP-INVARIANT above */
break; /* Cause p to be overwritten by pTemplate */
}
}
return ppPrev;
}
/*
** Insert or replace a WhereLoop entry using the template supplied.
**
** An existing WhereLoop entry might be overwritten if the new template
** is better and has fewer dependencies. Or the template will be ignored
** and no insert will occur if an existing WhereLoop is faster and has
** fewer dependencies than the template. Otherwise a new WhereLoop is
** added based on the template.
**
** If pBuilder->pOrSet is not NULL then we care about only the
** prerequisites and rRun and nOut costs of the N best loops. That
** information is gathered in the pBuilder->pOrSet object. This special
** processing mode is used only for OR clause processing.
**
** When accumulating multiple loops (when pBuilder->pOrSet is NULL) we
** still might overwrite similar loops with the new template if the
** new template is better. Loops may be overwritten if the following
** conditions are met:
**
** (1) They have the same iTab.
** (2) They have the same iSortIdx.
** (3) The template has same or fewer dependencies than the current loop
** (4) The template has the same or lower cost than the current loop
*/
static int whereLoopInsert(WhereLoopBuilder *pBuilder, WhereLoop *pTemplate){
WhereLoop **ppPrev, *p;
WhereInfo *pWInfo = pBuilder->pWInfo;
sqlite3 *db = pWInfo->pParse->db;
/* If pBuilder->pOrSet is defined, then only keep track of the costs
** and prereqs.
*/
if( pBuilder->pOrSet!=0 ){
if( pTemplate->nLTerm ){
#if WHERETRACE_ENABLED
u16 n = pBuilder->pOrSet->n;
int x =
#endif
whereOrInsert(pBuilder->pOrSet, pTemplate->prereq, pTemplate->rRun,
pTemplate->nOut);
#if WHERETRACE_ENABLED /* 0x8 */
if( sqlite3WhereTrace & 0x8 ){
sqlite3DebugPrintf(x?" or-%d: ":" or-X: ", n);
whereLoopPrint(pTemplate, pBuilder->pWC);
}
#endif
}
return SQLITE_OK;
}
/* Look for an existing WhereLoop to replace with pTemplate
*/
whereLoopAdjustCost(pWInfo->pLoops, pTemplate);
ppPrev = whereLoopFindLesser(&pWInfo->pLoops, pTemplate);
if( ppPrev==0 ){
/* There already exists a WhereLoop on the list that is better
** than pTemplate, so just ignore pTemplate */
#if WHERETRACE_ENABLED /* 0x8 */
if( sqlite3WhereTrace & 0x8 ){
sqlite3DebugPrintf(" skip: ");
whereLoopPrint(pTemplate, pBuilder->pWC);
}
#endif
return SQLITE_OK;
}else{
p = *ppPrev;
}
/* If we reach this point it means that either p[] should be overwritten
** with pTemplate[] if p[] exists, or if p==NULL then allocate a new
** WhereLoop and insert it.
*/
#if WHERETRACE_ENABLED /* 0x8 */
if( sqlite3WhereTrace & 0x8 ){
if( p!=0 ){
sqlite3DebugPrintf("replace: ");
whereLoopPrint(p, pBuilder->pWC);
}
sqlite3DebugPrintf(" add: ");
whereLoopPrint(pTemplate, pBuilder->pWC);
}
#endif
if( p==0 ){
/* Allocate a new WhereLoop to add to the end of the list */
*ppPrev = p = sqlite3DbMallocRaw(db, sizeof(WhereLoop));
if( p==0 ) return SQLITE_NOMEM;
whereLoopInit(p);
p->pNextLoop = 0;
}else{
/* We will be overwriting WhereLoop p[]. But before we do, first
** go through the rest of the list and delete any other entries besides
** p[] that are also supplated by pTemplate */
WhereLoop **ppTail = &p->pNextLoop;
WhereLoop *pToDel;
while( *ppTail ){
ppTail = whereLoopFindLesser(ppTail, pTemplate);
if( ppTail==0 ) break;
pToDel = *ppTail;
if( pToDel==0 ) break;
*ppTail = pToDel->pNextLoop;
#if WHERETRACE_ENABLED /* 0x8 */
if( sqlite3WhereTrace & 0x8 ){
sqlite3DebugPrintf(" delete: ");
whereLoopPrint(pToDel, pBuilder->pWC);
}
#endif
whereLoopDelete(db, pToDel);
}
}
whereLoopXfer(db, p, pTemplate);
if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){
Index *pIndex = p->u.btree.pIndex;
if( pIndex && pIndex->tnum==0 ){
p->u.btree.pIndex = 0;
}
}
return SQLITE_OK;
}
/*
** Adjust the WhereLoop.nOut value downward to account for terms of the
** WHERE clause that reference the loop but which are not used by an
** index.
*
** For every WHERE clause term that is not used by the index
** and which has a truth probability assigned by one of the likelihood(),
** likely(), or unlikely() SQL functions, reduce the estimated number
** of output rows by the probability specified.
**
** TUNING: For every WHERE clause term that is not used by the index
** and which does not have an assigned truth probability, heuristics
** described below are used to try to estimate the truth probability.
** TODO --> Perhaps this is something that could be improved by better
** table statistics.
**
** Heuristic 1: Estimate the truth probability as 93.75%. The 93.75%
** value corresponds to -1 in LogEst notation, so this means decrement
** the WhereLoop.nOut field for every such WHERE clause term.
**
** Heuristic 2: If there exists one or more WHERE clause terms of the
** form "x==EXPR" and EXPR is not a constant 0 or 1, then make sure the
** final output row estimate is no greater than 1/4 of the total number
** of rows in the table. In other words, assume that x==EXPR will filter
** out at least 3 out of 4 rows. If EXPR is -1 or 0 or 1, then maybe the
** "x" column is boolean or else -1 or 0 or 1 is a common default value
** on the "x" column and so in that case only cap the output row estimate
** at 1/2 instead of 1/4.
*/
static void whereLoopOutputAdjust(
WhereClause *pWC, /* The WHERE clause */
WhereLoop *pLoop, /* The loop to adjust downward */
LogEst nRow /* Number of rows in the entire table */
){
WhereTerm *pTerm, *pX;
Bitmask notAllowed = ~(pLoop->prereq|pLoop->maskSelf);
int i, j, k;
LogEst iReduce = 0; /* pLoop->nOut should not exceed nRow-iReduce */
assert( (pLoop->wsFlags & WHERE_AUTO_INDEX)==0 );
for(i=pWC->nTerm, pTerm=pWC->a; i>0; i--, pTerm++){
if( (pTerm->wtFlags & TERM_VIRTUAL)!=0 ) break;
if( (pTerm->prereqAll & pLoop->maskSelf)==0 ) continue;
if( (pTerm->prereqAll & notAllowed)!=0 ) continue;
for(j=pLoop->nLTerm-1; j>=0; j--){
pX = pLoop->aLTerm[j];
if( pX==0 ) continue;
if( pX==pTerm ) break;
if( pX->iParent>=0 && (&pWC->a[pX->iParent])==pTerm ) break;
}
if( j<0 ){
if( pTerm->truthProb<=0 ){
/* If a truth probability is specified using the likelihood() hints,
** then use the probability provided by the application. */
pLoop->nOut += pTerm->truthProb;
}else{
/* In the absence of explicit truth probabilities, use heuristics to
** guess a reasonable truth probability. */
pLoop->nOut--;
if( pTerm->eOperator&(WO_EQ|WO_IS) ){
Expr *pRight = pTerm->pExpr->pRight;
testcase( pTerm->pExpr->op==TK_IS );
if( sqlite3ExprIsInteger(pRight, &k) && k>=(-1) && k<=1 ){
k = 10;
}else{
k = 20;
}
if( iReduce<k ) iReduce = k;
}
}
}
}
if( pLoop->nOut > nRow-iReduce ) pLoop->nOut = nRow - iReduce;
}
/*
** Adjust the cost C by the costMult facter T. This only occurs if
** compiled with -DSQLITE_ENABLE_COSTMULT
*/
#ifdef SQLITE_ENABLE_COSTMULT
# define ApplyCostMultiplier(C,T) C += T
#else
# define ApplyCostMultiplier(C,T)
#endif
/*
** We have so far matched pBuilder->pNew->u.btree.nEq terms of the
** index pIndex. Try to match one more.
**
** When this function is called, pBuilder->pNew->nOut contains the
** number of rows expected to be visited by filtering using the nEq
** terms only. If it is modified, this value is restored before this
** function returns.
**
** If pProbe->tnum==0, that means pIndex is a fake index used for the
** INTEGER PRIMARY KEY.
*/
static int whereLoopAddBtreeIndex(
WhereLoopBuilder *pBuilder, /* The WhereLoop factory */
struct SrcList_item *pSrc, /* FROM clause term being analyzed */
Index *pProbe, /* An index on pSrc */
LogEst nInMul /* log(Number of iterations due to IN) */
){
WhereInfo *pWInfo = pBuilder->pWInfo; /* WHERE analyse context */
Parse *pParse = pWInfo->pParse; /* Parsing context */
sqlite3 *db = pParse->db; /* Database connection malloc context */
WhereLoop *pNew; /* Template WhereLoop under construction */
WhereTerm *pTerm; /* A WhereTerm under consideration */
int opMask; /* Valid operators for constraints */
WhereScan scan; /* Iterator for WHERE terms */
Bitmask saved_prereq; /* Original value of pNew->prereq */
u16 saved_nLTerm; /* Original value of pNew->nLTerm */
u16 saved_nEq; /* Original value of pNew->u.btree.nEq */
u16 saved_nSkip; /* Original value of pNew->nSkip */
u32 saved_wsFlags; /* Original value of pNew->wsFlags */
LogEst saved_nOut; /* Original value of pNew->nOut */
int rc = SQLITE_OK; /* Return code */
LogEst rSize; /* Number of rows in the table */
LogEst rLogSize; /* Logarithm of table size */
WhereTerm *pTop = 0, *pBtm = 0; /* Top and bottom range constraints */
pNew = pBuilder->pNew;
if( db->mallocFailed ) return SQLITE_NOMEM;
assert( (pNew->wsFlags & WHERE_VIRTUALTABLE)==0 );
assert( (pNew->wsFlags & WHERE_TOP_LIMIT)==0 );
if( pNew->wsFlags & WHERE_BTM_LIMIT ){
opMask = WO_LT|WO_LE;
}else if( /*pProbe->tnum<=0 ||*/ (pSrc->fg.jointype & JT_LEFT)!=0 ){
opMask = WO_EQ|WO_IN|WO_GT|WO_GE|WO_LT|WO_LE;
}else{
opMask = WO_EQ|WO_IN|WO_GT|WO_GE|WO_LT|WO_LE|WO_ISNULL|WO_IS;
}
if( pProbe->bUnordered ) opMask &= ~(WO_GT|WO_GE|WO_LT|WO_LE);
assert( pNew->u.btree.nEq<pProbe->nColumn );
saved_nEq = pNew->u.btree.nEq;
saved_nSkip = pNew->nSkip;
saved_nLTerm = pNew->nLTerm;
saved_wsFlags = pNew->wsFlags;
saved_prereq = pNew->prereq;
saved_nOut = pNew->nOut;
pTerm = whereScanInit(&scan, pBuilder->pWC, pSrc->iCursor, saved_nEq,
opMask, pProbe);
pNew->rSetup = 0;
rSize = pProbe->aiRowLogEst[0];
rLogSize = estLog(rSize);
for(; rc==SQLITE_OK && pTerm!=0; pTerm = whereScanNext(&scan)){
u16 eOp = pTerm->eOperator; /* Shorthand for pTerm->eOperator */
LogEst rCostIdx;
LogEst nOutUnadjusted; /* nOut before IN() and WHERE adjustments */
int nIn = 0;
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
int nRecValid = pBuilder->nRecValid;
#endif
if( (eOp==WO_ISNULL || (pTerm->wtFlags&TERM_VNULL)!=0)
&& indexColumnNotNull(pProbe, saved_nEq)
){
continue; /* ignore IS [NOT] NULL constraints on NOT NULL columns */
}
if( pTerm->prereqRight & pNew->maskSelf ) continue;
/* Do not allow the upper bound of a LIKE optimization range constraint
** to mix with a lower range bound from some other source */
if( pTerm->wtFlags & TERM_LIKEOPT && pTerm->eOperator==WO_LT ) continue;
pNew->wsFlags = saved_wsFlags;
pNew->u.btree.nEq = saved_nEq;
pNew->nLTerm = saved_nLTerm;
if( whereLoopResize(db, pNew, pNew->nLTerm+1) ) break; /* OOM */
pNew->aLTerm[pNew->nLTerm++] = pTerm;
pNew->prereq = (saved_prereq | pTerm->prereqRight) & ~pNew->maskSelf;
assert( nInMul==0
|| (pNew->wsFlags & WHERE_COLUMN_NULL)!=0
|| (pNew->wsFlags & WHERE_COLUMN_IN)!=0
|| (pNew->wsFlags & WHERE_SKIPSCAN)!=0
);
if( eOp & WO_IN ){
Expr *pExpr = pTerm->pExpr;
pNew->wsFlags |= WHERE_COLUMN_IN;
if( ExprHasProperty(pExpr, EP_xIsSelect) ){
/* "x IN (SELECT ...)": TUNING: the SELECT returns 25 rows */
nIn = 46; assert( 46==sqlite3LogEst(25) );
}else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){
/* "x IN (value, value, ...)" */
nIn = sqlite3LogEst(pExpr->x.pList->nExpr);
}
assert( nIn>0 ); /* RHS always has 2 or more terms... The parser
** changes "x IN (?)" into "x=?". */
}else if( eOp & (WO_EQ|WO_IS) ){
int iCol = pProbe->aiColumn[saved_nEq];
pNew->wsFlags |= WHERE_COLUMN_EQ;
assert( saved_nEq==pNew->u.btree.nEq );
if( iCol==XN_ROWID
|| (iCol>0 && nInMul==0 && saved_nEq==pProbe->nKeyCol-1)
){
if( iCol>=0 && pProbe->uniqNotNull==0 ){
pNew->wsFlags |= WHERE_UNQ_WANTED;
}else{
pNew->wsFlags |= WHERE_ONEROW;
}
}
}else if( eOp & WO_ISNULL ){
pNew->wsFlags |= WHERE_COLUMN_NULL;
}else if( eOp & (WO_GT|WO_GE) ){
testcase( eOp & WO_GT );
testcase( eOp & WO_GE );
pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_BTM_LIMIT;
pBtm = pTerm;
pTop = 0;
if( pTerm->wtFlags & TERM_LIKEOPT ){
/* Range contraints that come from the LIKE optimization are
** always used in pairs. */
pTop = &pTerm[1];
assert( (pTop-(pTerm->pWC->a))<pTerm->pWC->nTerm );
assert( pTop->wtFlags & TERM_LIKEOPT );
assert( pTop->eOperator==WO_LT );
if( whereLoopResize(db, pNew, pNew->nLTerm+1) ) break; /* OOM */
pNew->aLTerm[pNew->nLTerm++] = pTop;
pNew->wsFlags |= WHERE_TOP_LIMIT;
}
}else{
assert( eOp & (WO_LT|WO_LE) );
testcase( eOp & WO_LT );
testcase( eOp & WO_LE );
pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_TOP_LIMIT;
pTop = pTerm;
pBtm = (pNew->wsFlags & WHERE_BTM_LIMIT)!=0 ?
pNew->aLTerm[pNew->nLTerm-2] : 0;
}
/* At this point pNew->nOut is set to the number of rows expected to
** be visited by the index scan before considering term pTerm, or the
** values of nIn and nInMul. In other words, assuming that all
** "x IN(...)" terms are replaced with "x = ?". This block updates
** the value of pNew->nOut to account for pTerm (but not nIn/nInMul). */
assert( pNew->nOut==saved_nOut );
if( pNew->wsFlags & WHERE_COLUMN_RANGE ){
/* Adjust nOut using stat3/stat4 data. Or, if there is no stat3/stat4
** data, using some other estimate. */
whereRangeScanEst(pParse, pBuilder, pBtm, pTop, pNew);
}else{
int nEq = ++pNew->u.btree.nEq;
assert( eOp & (WO_ISNULL|WO_EQ|WO_IN|WO_IS) );
assert( pNew->nOut==saved_nOut );
if( pTerm->truthProb<=0 && pProbe->aiColumn[saved_nEq]>=0 ){
assert( (eOp & WO_IN) || nIn==0 );
testcase( eOp & WO_IN );
pNew->nOut += pTerm->truthProb;
pNew->nOut -= nIn;
}else{
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
tRowcnt nOut = 0;
if( nInMul==0
&& pProbe->nSample
&& pNew->u.btree.nEq<=pProbe->nSampleCol
&& ((eOp & WO_IN)==0 || !ExprHasProperty(pTerm->pExpr, EP_xIsSelect))
){
Expr *pExpr = pTerm->pExpr;
if( (eOp & (WO_EQ|WO_ISNULL|WO_IS))!=0 ){
testcase( eOp & WO_EQ );
testcase( eOp & WO_IS );
testcase( eOp & WO_ISNULL );
rc = whereEqualScanEst(pParse, pBuilder, pExpr->pRight, &nOut);
}else{
rc = whereInScanEst(pParse, pBuilder, pExpr->x.pList, &nOut);
}
if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK;
if( rc!=SQLITE_OK ) break; /* Jump out of the pTerm loop */
if( nOut ){
pNew->nOut = sqlite3LogEst(nOut);
if( pNew->nOut>saved_nOut ) pNew->nOut = saved_nOut;
pNew->nOut -= nIn;
}
}
if( nOut==0 )
#endif
{
pNew->nOut += (pProbe->aiRowLogEst[nEq] - pProbe->aiRowLogEst[nEq-1]);
if( eOp & WO_ISNULL ){
/* TUNING: If there is no likelihood() value, assume that a
** "col IS NULL" expression matches twice as many rows
** as (col=?). */
pNew->nOut += 10;
}
}
}
}
/* Set rCostIdx to the cost of visiting selected rows in index. Add
** it to pNew->rRun, which is currently set to the cost of the index
** seek only. Then, if this is a non-covering index, add the cost of
** visiting the rows in the main table. */
rCostIdx = pNew->nOut + 1 + (15*pProbe->szIdxRow)/pSrc->pTab->szTabRow;
pNew->rRun = sqlite3LogEstAdd(rLogSize, rCostIdx);
if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK))==0 ){
pNew->rRun = sqlite3LogEstAdd(pNew->rRun, pNew->nOut + 16);
}
ApplyCostMultiplier(pNew->rRun, pProbe->pTable->costMult);
nOutUnadjusted = pNew->nOut;
pNew->rRun += nInMul + nIn;
pNew->nOut += nInMul + nIn;
whereLoopOutputAdjust(pBuilder->pWC, pNew, rSize);
rc = whereLoopInsert(pBuilder, pNew);
if( pNew->wsFlags & WHERE_COLUMN_RANGE ){
pNew->nOut = saved_nOut;
}else{
pNew->nOut = nOutUnadjusted;
}
if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0
&& pNew->u.btree.nEq<pProbe->nColumn
){
whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn);
}
pNew->nOut = saved_nOut;
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
pBuilder->nRecValid = nRecValid;
#endif
}
pNew->prereq = saved_prereq;
pNew->u.btree.nEq = saved_nEq;
pNew->nSkip = saved_nSkip;
pNew->wsFlags = saved_wsFlags;
pNew->nOut = saved_nOut;
pNew->nLTerm = saved_nLTerm;
/* Consider using a skip-scan if there are no WHERE clause constraints
** available for the left-most terms of the index, and if the average
** number of repeats in the left-most terms is at least 18.
**
** The magic number 18 is selected on the basis that scanning 17 rows
** is almost always quicker than an index seek (even though if the index
** contains fewer than 2^17 rows we assume otherwise in other parts of
** the code). And, even if it is not, it should not be too much slower.
** On the other hand, the extra seeks could end up being significantly
** more expensive. */
assert( 42==sqlite3LogEst(18) );
if( saved_nEq==saved_nSkip
&& saved_nEq+1<pProbe->nKeyCol
&& pProbe->noSkipScan==0
&& pProbe->aiRowLogEst[saved_nEq+1]>=42 /* TUNING: Minimum for skip-scan */
&& (rc = whereLoopResize(db, pNew, pNew->nLTerm+1))==SQLITE_OK
){
LogEst nIter;
pNew->u.btree.nEq++;
pNew->nSkip++;
pNew->aLTerm[pNew->nLTerm++] = 0;
pNew->wsFlags |= WHERE_SKIPSCAN;
nIter = pProbe->aiRowLogEst[saved_nEq] - pProbe->aiRowLogEst[saved_nEq+1];
pNew->nOut -= nIter;
/* TUNING: Because uncertainties in the estimates for skip-scan queries,
** add a 1.375 fudge factor to make skip-scan slightly less likely. */
nIter += 5;
whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nIter + nInMul);
pNew->nOut = saved_nOut;
pNew->u.btree.nEq = saved_nEq;
pNew->nSkip = saved_nSkip;
pNew->wsFlags = saved_wsFlags;
}
return rc;
}
/*
** Return True if it is possible that pIndex might be useful in
** implementing the ORDER BY clause in pBuilder.
**
** Return False if pBuilder does not contain an ORDER BY clause or
** if there is no way for pIndex to be useful in implementing that
** ORDER BY clause.
*/
static int indexMightHelpWithOrderBy(
WhereLoopBuilder *pBuilder,
Index *pIndex,
int iCursor
){
ExprList *pOB;
ExprList *aColExpr;
int ii, jj;
if( pIndex->bUnordered ) return 0;
if( (pOB = pBuilder->pWInfo->pOrderBy)==0 ) return 0;
for(ii=0; ii<pOB->nExpr; ii++){
Expr *pExpr = sqlite3ExprSkipCollate(pOB->a[ii].pExpr);
if( pExpr->op==TK_COLUMN && pExpr->iTable==iCursor ){
if( pExpr->iColumn<0 ) return 1;
for(jj=0; jj<pIndex->nKeyCol; jj++){
if( pExpr->iColumn==pIndex->aiColumn[jj] ) return 1;
}
}else if( (aColExpr = pIndex->aColExpr)!=0 ){
for(jj=0; jj<pIndex->nKeyCol; jj++){
if( pIndex->aiColumn[jj]!=XN_EXPR ) continue;
if( sqlite3ExprCompare(pExpr,aColExpr->a[jj].pExpr,iCursor)==0 ){
return 1;
}
}
}
}
return 0;
}
/*
** Return a bitmask where 1s indicate that the corresponding column of
** the table is used by an index. Only the first 63 columns are considered.
*/
static Bitmask columnsInIndex(Index *pIdx){
Bitmask m = 0;
int j;
for(j=pIdx->nColumn-1; j>=0; j--){
int x = pIdx->aiColumn[j];
if( x>=0 ){
testcase( x==BMS-1 );
testcase( x==BMS-2 );
if( x<BMS-1 ) m |= MASKBIT(x);
}
}
return m;
}
/* Check to see if a partial index with pPartIndexWhere can be used
** in the current query. Return true if it can be and false if not.
*/
static int whereUsablePartialIndex(int iTab, WhereClause *pWC, Expr *pWhere){
int i;
WhereTerm *pTerm;
while( pWhere->op==TK_AND ){
if( !whereUsablePartialIndex(iTab,pWC,pWhere->pLeft) ) return 0;
pWhere = pWhere->pRight;
}
for(i=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
Expr *pExpr = pTerm->pExpr;
if( sqlite3ExprImpliesExpr(pExpr, pWhere, iTab)
&& (!ExprHasProperty(pExpr, EP_FromJoin) || pExpr->iRightJoinTable==iTab)
){
return 1;
}
}
return 0;
}
/*
** Add all WhereLoop objects for a single table of the join where the table
** is idenfied by pBuilder->pNew->iTab. That table is guaranteed to be
** a b-tree table, not a virtual table.
**
** The costs (WhereLoop.rRun) of the b-tree loops added by this function
** are calculated as follows:
**
** For a full scan, assuming the table (or index) contains nRow rows:
**
** cost = nRow * 3.0 // full-table scan
** cost = nRow * K // scan of covering index
** cost = nRow * (K+3.0) // scan of non-covering index
**
** where K is a value between 1.1 and 3.0 set based on the relative
** estimated average size of the index and table records.
**
** For an index scan, where nVisit is the number of index rows visited
** by the scan, and nSeek is the number of seek operations required on
** the index b-tree:
**
** cost = nSeek * (log(nRow) + K * nVisit) // covering index
** cost = nSeek * (log(nRow) + (K+3.0) * nVisit) // non-covering index
**
** Normally, nSeek is 1. nSeek values greater than 1 come about if the
** WHERE clause includes "x IN (....)" terms used in place of "x=?". Or when
** implicit "x IN (SELECT x FROM tbl)" terms are added for skip-scans.
**
** The estimated values (nRow, nVisit, nSeek) often contain a large amount
** of uncertainty. For this reason, scoring is designed to pick plans that
** "do the least harm" if the estimates are inaccurate. For example, a
** log(nRow) factor is omitted from a non-covering index scan in order to
** bias the scoring in favor of using an index, since the worst-case
** performance of using an index is far better than the worst-case performance
** of a full table scan.
*/
static int whereLoopAddBtree(
WhereLoopBuilder *pBuilder, /* WHERE clause information */
Bitmask mExtra /* Extra prerequesites for using this table */
){
WhereInfo *pWInfo; /* WHERE analysis context */
Index *pProbe; /* An index we are evaluating */
Index sPk; /* A fake index object for the primary key */
LogEst aiRowEstPk[2]; /* The aiRowLogEst[] value for the sPk index */
i16 aiColumnPk = -1; /* The aColumn[] value for the sPk index */
SrcList *pTabList; /* The FROM clause */
struct SrcList_item *pSrc; /* The FROM clause btree term to add */
WhereLoop *pNew; /* Template WhereLoop object */
int rc = SQLITE_OK; /* Return code */
int iSortIdx = 1; /* Index number */
int b; /* A boolean value */
LogEst rSize; /* number of rows in the table */
LogEst rLogSize; /* Logarithm of the number of rows in the table */
WhereClause *pWC; /* The parsed WHERE clause */
Table *pTab; /* Table being queried */
pNew = pBuilder->pNew;
pWInfo = pBuilder->pWInfo;
pTabList = pWInfo->pTabList;
pSrc = pTabList->a + pNew->iTab;
pTab = pSrc->pTab;
pWC = pBuilder->pWC;
assert( !IsVirtual(pSrc->pTab) );
if( pSrc->pIBIndex ){
/* An INDEXED BY clause specifies a particular index to use */
pProbe = pSrc->pIBIndex;
}else if( !HasRowid(pTab) ){
pProbe = pTab->pIndex;
}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.nKeyCol = 1;
sPk.nColumn = 1;
sPk.aiColumn = &aiColumnPk;
sPk.aiRowLogEst = aiRowEstPk;
sPk.onError = OE_Replace;
sPk.pTable = pTab;
sPk.szIdxRow = pTab->szTabRow;
aiRowEstPk[0] = pTab->nRowLogEst;
aiRowEstPk[1] = 0;
pFirst = pSrc->pTab->pIndex;
if( pSrc->fg.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;
}
rSize = pTab->nRowLogEst;
rLogSize = estLog(rSize);
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
/* Automatic indexes */
if( !pBuilder->pOrSet /* Not part of an OR optimization */
&& (pWInfo->wctrlFlags & WHERE_NO_AUTOINDEX)==0
&& (pWInfo->pParse->db->flags & SQLITE_AutoIndex)!=0
&& pSrc->pIBIndex==0 /* Has no INDEXED BY clause */
&& !pSrc->fg.notIndexed /* Has no NOT INDEXED clause */
&& HasRowid(pTab) /* Not WITHOUT ROWID table. (FIXME: Why not?) */
&& !pSrc->fg.isCorrelated /* Not a correlated subquery */
&& !pSrc->fg.isRecursive /* Not a recursive common table expression. */
){
/* Generate auto-index WhereLoops */
WhereTerm *pTerm;
WhereTerm *pWCEnd = pWC->a + pWC->nTerm;
for(pTerm=pWC->a; rc==SQLITE_OK && pTerm<pWCEnd; pTerm++){
if( pTerm->prereqRight & pNew->maskSelf ) continue;
if( termCanDriveIndex(pTerm, pSrc, 0) ){
pNew->u.btree.nEq = 1;
pNew->nSkip = 0;
pNew->u.btree.pIndex = 0;
pNew->nLTerm = 1;
pNew->aLTerm[0] = pTerm;
/* TUNING: One-time cost for computing the automatic index is
** estimated to be X*N*log2(N) where N is the number of rows in
** the table being indexed and where X is 7 (LogEst=28) for normal
** tables or 1.375 (LogEst=4) for views and subqueries. The value
** of X is smaller for views and subqueries so that the query planner
** will be more aggressive about generating automatic indexes for
** those objects, since there is no opportunity to add schema
** indexes on subqueries and views. */
pNew->rSetup = rLogSize + rSize + 4;
if( pTab->pSelect==0 && (pTab->tabFlags & TF_Ephemeral)==0 ){
pNew->rSetup += 24;
}
ApplyCostMultiplier(pNew->rSetup, pTab->costMult);
/* TUNING: Each index lookup yields 20 rows in the table. This
** is more than the usual guess of 10 rows, since we have no way
** of knowing how selective the index will ultimately be. It would
** not be unreasonable to make this value much larger. */
pNew->nOut = 43; assert( 43==sqlite3LogEst(20) );
pNew->rRun = sqlite3LogEstAdd(rLogSize,pNew->nOut);
pNew->wsFlags = WHERE_AUTO_INDEX;
pNew->prereq = mExtra | pTerm->prereqRight;
rc = whereLoopInsert(pBuilder, pNew);
}
}
}
#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */
/* Loop over all indices
*/
for(; rc==SQLITE_OK && pProbe; pProbe=pProbe->pNext, iSortIdx++){
if( pProbe->pPartIdxWhere!=0
&& !whereUsablePartialIndex(pSrc->iCursor, pWC, pProbe->pPartIdxWhere) ){
testcase( pNew->iTab!=pSrc->iCursor ); /* See ticket [98d973b8f5] */
continue; /* Partial index inappropriate for this query */
}
rSize = pProbe->aiRowLogEst[0];
pNew->u.btree.nEq = 0;
pNew->nSkip = 0;
pNew->nLTerm = 0;
pNew->iSortIdx = 0;
pNew->rSetup = 0;
pNew->prereq = mExtra;
pNew->nOut = rSize;
pNew->u.btree.pIndex = pProbe;
b = indexMightHelpWithOrderBy(pBuilder, pProbe, pSrc->iCursor);
/* The ONEPASS_DESIRED flags never occurs together with ORDER BY */
assert( (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || b==0 );
if( pProbe->tnum<=0 ){
/* Integer primary key index */
pNew->wsFlags = WHERE_IPK;
/* Full table scan */
pNew->iSortIdx = b ? iSortIdx : 0;
/* TUNING: Cost of full table scan is (N*3.0). */
pNew->rRun = rSize + 16;
ApplyCostMultiplier(pNew->rRun, pTab->costMult);
whereLoopOutputAdjust(pWC, pNew, rSize);
rc = whereLoopInsert(pBuilder, pNew);
pNew->nOut = rSize;
if( rc ) break;
}else{
Bitmask m;
if( pProbe->isCovering ){
pNew->wsFlags = WHERE_IDX_ONLY | WHERE_INDEXED;
m = 0;
}else{
m = pSrc->colUsed & ~columnsInIndex(pProbe);
pNew->wsFlags = (m==0) ? (WHERE_IDX_ONLY|WHERE_INDEXED) : WHERE_INDEXED;
}
/* Full scan via index */
if( b
|| !HasRowid(pTab)
|| ( m==0
&& pProbe->bUnordered==0
&& (pProbe->szIdxRow<pTab->szTabRow)
&& (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0
&& sqlite3GlobalConfig.bUseCis
&& OptimizationEnabled(pWInfo->pParse->db, SQLITE_CoverIdxScan)
)
){
pNew->iSortIdx = b ? iSortIdx : 0;
/* The cost of visiting the index rows is N*K, where K is
** between 1.1 and 3.0, depending on the relative sizes of the
** index and table rows. If this is a non-covering index scan,
** also add the cost of visiting table rows (N*3.0). */
pNew->rRun = rSize + 1 + (15*pProbe->szIdxRow)/pTab->szTabRow;
if( m!=0 ){
pNew->rRun = sqlite3LogEstAdd(pNew->rRun, rSize+16);
}
ApplyCostMultiplier(pNew->rRun, pTab->costMult);
whereLoopOutputAdjust(pWC, pNew, rSize);
rc = whereLoopInsert(pBuilder, pNew);
pNew->nOut = rSize;
if( rc ) break;
}
}
rc = whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, 0);
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
sqlite3Stat4ProbeFree(pBuilder->pRec);
pBuilder->nRecValid = 0;
pBuilder->pRec = 0;
#endif
/* If there was an INDEXED BY clause, then only that one index is
** considered. */
if( pSrc->pIBIndex ) break;
}
return rc;
}
#ifndef SQLITE_OMIT_VIRTUALTABLE
/*
** Add all WhereLoop objects for a table of the join identified by
** pBuilder->pNew->iTab. That table is guaranteed to be a virtual table.
**
** If there are no LEFT or CROSS JOIN joins in the query, both mExtra and
** mUnusable are set to 0. Otherwise, mExtra is a mask of all FROM clause
** entries that occur before the virtual table in the FROM clause and are
** separated from it by at least one LEFT or CROSS JOIN. Similarly, the
** mUnusable mask contains all FROM clause entries that occur after the
** virtual table and are separated from it by at least one LEFT or
** CROSS JOIN.
**
** For example, if the query were:
**
** ... FROM t1, t2 LEFT JOIN t3, t4, vt CROSS JOIN t5, t6;
**
** then mExtra corresponds to (t1, t2) and mUnusable to (t5, t6).
**
** All the tables in mExtra must be scanned before the current virtual
** table. So any terms for which all prerequisites are satisfied by
** mExtra may be specified as "usable" in all calls to xBestIndex.
** Conversely, all tables in mUnusable must be scanned after the current
** virtual table, so any terms for which the prerequisites overlap with
** mUnusable should always be configured as "not-usable" for xBestIndex.
*/
static int whereLoopAddVirtual(
WhereLoopBuilder *pBuilder, /* WHERE clause information */
Bitmask mExtra, /* Tables that must be scanned before this one */
Bitmask mUnusable /* Tables that must be scanned after this one */
){
WhereInfo *pWInfo; /* WHERE analysis context */
Parse *pParse; /* The parsing context */
WhereClause *pWC; /* The WHERE clause */
struct SrcList_item *pSrc; /* The FROM clause term to search */
Table *pTab;
sqlite3 *db;
sqlite3_index_info *pIdxInfo;
struct sqlite3_index_constraint *pIdxCons;
struct sqlite3_index_constraint_usage *pUsage;
WhereTerm *pTerm;
int i, j;
int iTerm, mxTerm;
int nConstraint;
int seenIn = 0; /* True if an IN operator is seen */
int seenVar = 0; /* True if a non-constant constraint is seen */
int iPhase; /* 0: const w/o IN, 1: const, 2: no IN, 2: IN */
WhereLoop *pNew;
int rc = SQLITE_OK;
assert( (mExtra & mUnusable)==0 );
pWInfo = pBuilder->pWInfo;
pParse = pWInfo->pParse;
db = pParse->db;
pWC = pBuilder->pWC;
pNew = pBuilder->pNew;
pSrc = &pWInfo->pTabList->a[pNew->iTab];
pTab = pSrc->pTab;
assert( IsVirtual(pTab) );
pIdxInfo = allocateIndexInfo(pParse, pWC, mUnusable, pSrc,pBuilder->pOrderBy);
if( pIdxInfo==0 ) return SQLITE_NOMEM;
pNew->prereq = 0;
pNew->rSetup = 0;
pNew->wsFlags = WHERE_VIRTUALTABLE;
pNew->nLTerm = 0;
pNew->u.vtab.needFree = 0;
pUsage = pIdxInfo->aConstraintUsage;
nConstraint = pIdxInfo->nConstraint;
if( whereLoopResize(db, pNew, nConstraint) ){
sqlite3DbFree(db, pIdxInfo);
return SQLITE_NOMEM;
}
for(iPhase=0; iPhase<=3; iPhase++){
if( !seenIn && (iPhase&1)!=0 ){
iPhase++;
if( iPhase>3 ) break;
}
if( !seenVar && iPhase>1 ) break;
pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
for(i=0; i<pIdxInfo->nConstraint; i++, pIdxCons++){
j = pIdxCons->iTermOffset;
pTerm = &pWC->a[j];
switch( iPhase ){
case 0: /* Constants without IN operator */
pIdxCons->usable = 0;
if( (pTerm->eOperator & WO_IN)!=0 ){
seenIn = 1;
}
if( (pTerm->prereqRight & ~mExtra)!=0 ){
seenVar = 1;
}else if( (pTerm->eOperator & WO_IN)==0 ){
pIdxCons->usable = 1;
}
break;
case 1: /* Constants with IN operators */
assert( seenIn );
pIdxCons->usable = (pTerm->prereqRight & ~mExtra)==0;
break;
case 2: /* Variables without IN */
assert( seenVar );
pIdxCons->usable = (pTerm->eOperator & WO_IN)==0;
break;
default: /* Variables with IN */
assert( seenVar && seenIn );
pIdxCons->usable = 1;
break;
}
}
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;
pIdxInfo->estimatedCost = SQLITE_BIG_DBL / (double)2;
pIdxInfo->estimatedRows = 25;
pIdxInfo->idxFlags = 0;
pIdxInfo->colUsed = (sqlite3_int64)pSrc->colUsed;
rc = vtabBestIndex(pParse, pTab, pIdxInfo);
if( rc ) goto whereLoopAddVtab_exit;
pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
pNew->prereq = mExtra;
mxTerm = -1;
assert( pNew->nLSlot>=nConstraint );
for(i=0; i<nConstraint; i++) pNew->aLTerm[i] = 0;
pNew->u.vtab.omitMask = 0;
for(i=0; i<nConstraint; i++, pIdxCons++){
if( (iTerm = pUsage[i].argvIndex - 1)>=0 ){
j = pIdxCons->iTermOffset;
if( iTerm>=nConstraint
|| j<0
|| j>=pWC->nTerm
|| pNew->aLTerm[iTerm]!=0
){
rc = SQLITE_ERROR;
sqlite3ErrorMsg(pParse, "%s.xBestIndex() malfunction", pTab->zName);
goto whereLoopAddVtab_exit;
}
testcase( iTerm==nConstraint-1 );
testcase( j==0 );
testcase( j==pWC->nTerm-1 );
pTerm = &pWC->a[j];
pNew->prereq |= pTerm->prereqRight;
assert( iTerm<pNew->nLSlot );
pNew->aLTerm[iTerm] = pTerm;
if( iTerm>mxTerm ) mxTerm = iTerm;
testcase( iTerm==15 );
testcase( iTerm==16 );
if( iTerm<16 && pUsage[i].omit ) pNew->u.vtab.omitMask |= 1<<iTerm;
if( (pTerm->eOperator & WO_IN)!=0 ){
if( pUsage[i].omit==0 ){
/* Do not attempt to use an IN constraint if the virtual table
** says that the equivalent EQ constraint cannot be safely omitted.
** If we do attempt to use such a constraint, some rows might be
** repeated in the output. */
break;
}
/* A virtual table that is constrained by an IN clause may not
** consume the ORDER BY clause because (1) the order of IN terms
** is not necessarily related to the order of output terms and
** (2) Multiple outputs from a single IN value will not merge
** together. */
pIdxInfo->orderByConsumed = 0;
pIdxInfo->idxFlags &= ~SQLITE_INDEX_SCAN_UNIQUE;
}
}
}
if( i>=nConstraint ){
pNew->nLTerm = mxTerm+1;
assert( pNew->nLTerm<=pNew->nLSlot );
pNew->u.vtab.idxNum = pIdxInfo->idxNum;
pNew->u.vtab.needFree = pIdxInfo->needToFreeIdxStr;
pIdxInfo->needToFreeIdxStr = 0;
pNew->u.vtab.idxStr = pIdxInfo->idxStr;
pNew->u.vtab.isOrdered = (i8)(pIdxInfo->orderByConsumed ?
pIdxInfo->nOrderBy : 0);
pNew->rSetup = 0;
pNew->rRun = sqlite3LogEstFromDouble(pIdxInfo->estimatedCost);
pNew->nOut = sqlite3LogEst(pIdxInfo->estimatedRows);
/* Set the WHERE_ONEROW flag if the xBestIndex() method indicated
** that the scan will visit at most one row. Clear it otherwise. */
if( pIdxInfo->idxFlags & SQLITE_INDEX_SCAN_UNIQUE ){
pNew->wsFlags |= WHERE_ONEROW;
}else{
pNew->wsFlags &= ~WHERE_ONEROW;
}
whereLoopInsert(pBuilder, pNew);
if( pNew->u.vtab.needFree ){
sqlite3_free(pNew->u.vtab.idxStr);
pNew->u.vtab.needFree = 0;
}
}
}
whereLoopAddVtab_exit:
if( pIdxInfo->needToFreeIdxStr ) sqlite3_free(pIdxInfo->idxStr);
sqlite3DbFree(db, pIdxInfo);
return rc;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */
/*
** Add WhereLoop entries to handle OR terms. This works for either
** btrees or virtual tables.
*/
static int whereLoopAddOr(
WhereLoopBuilder *pBuilder,
Bitmask mExtra,
Bitmask mUnusable
){
WhereInfo *pWInfo = pBuilder->pWInfo;
WhereClause *pWC;
WhereLoop *pNew;
WhereTerm *pTerm, *pWCEnd;
int rc = SQLITE_OK;
int iCur;
WhereClause tempWC;
WhereLoopBuilder sSubBuild;
WhereOrSet sSum, sCur;
struct SrcList_item *pItem;
pWC = pBuilder->pWC;
pWCEnd = pWC->a + pWC->nTerm;
pNew = pBuilder->pNew;
memset(&sSum, 0, sizeof(sSum));
pItem = pWInfo->pTabList->a + pNew->iTab;
iCur = pItem->iCursor;
for(pTerm=pWC->a; pTerm<pWCEnd && rc==SQLITE_OK; pTerm++){
if( (pTerm->eOperator & WO_OR)!=0
&& (pTerm->u.pOrInfo->indexable & pNew->maskSelf)!=0
){
WhereClause * const pOrWC = &pTerm->u.pOrInfo->wc;
WhereTerm * const pOrWCEnd = &pOrWC->a[pOrWC->nTerm];
WhereTerm *pOrTerm;
int once = 1;
int i, j;
sSubBuild = *pBuilder;
sSubBuild.pOrderBy = 0;
sSubBuild.pOrSet = &sCur;
WHERETRACE(0x200, ("Begin processing OR-clause %p\n", pTerm));
for(pOrTerm=pOrWC->a; pOrTerm<pOrWCEnd; pOrTerm++){
if( (pOrTerm->eOperator & WO_AND)!=0 ){
sSubBuild.pWC = &pOrTerm->u.pAndInfo->wc;
}else if( pOrTerm->leftCursor==iCur ){
tempWC.pWInfo = pWC->pWInfo;
tempWC.pOuter = pWC;
tempWC.op = TK_AND;
tempWC.nTerm = 1;
tempWC.a = pOrTerm;
sSubBuild.pWC = &tempWC;
}else{
continue;
}
sCur.n = 0;
#ifdef WHERETRACE_ENABLED
WHERETRACE(0x200, ("OR-term %d of %p has %d subterms:\n",
(int)(pOrTerm-pOrWC->a), pTerm, sSubBuild.pWC->nTerm));
if( sqlite3WhereTrace & 0x400 ){
for(i=0; i<sSubBuild.pWC->nTerm; i++){
whereTermPrint(&sSubBuild.pWC->a[i], i);
}
}
#endif
#ifndef SQLITE_OMIT_VIRTUALTABLE
if( IsVirtual(pItem->pTab) ){
rc = whereLoopAddVirtual(&sSubBuild, mExtra, mUnusable);
}else
#endif
{
rc = whereLoopAddBtree(&sSubBuild, mExtra);
}
if( rc==SQLITE_OK ){
rc = whereLoopAddOr(&sSubBuild, mExtra, mUnusable);
}
assert( rc==SQLITE_OK || sCur.n==0 );
if( sCur.n==0 ){
sSum.n = 0;
break;
}else if( once ){
whereOrMove(&sSum, &sCur);
once = 0;
}else{
WhereOrSet sPrev;
whereOrMove(&sPrev, &sSum);
sSum.n = 0;
for(i=0; i<sPrev.n; i++){
for(j=0; j<sCur.n; j++){
whereOrInsert(&sSum, sPrev.a[i].prereq | sCur.a[j].prereq,
sqlite3LogEstAdd(sPrev.a[i].rRun, sCur.a[j].rRun),
sqlite3LogEstAdd(sPrev.a[i].nOut, sCur.a[j].nOut));
}
}
}
}
pNew->nLTerm = 1;
pNew->aLTerm[0] = pTerm;
pNew->wsFlags = WHERE_MULTI_OR;
pNew->rSetup = 0;
pNew->iSortIdx = 0;
memset(&pNew->u, 0, sizeof(pNew->u));
for(i=0; rc==SQLITE_OK && i<sSum.n; i++){
/* TUNING: Currently sSum.a[i].rRun is set to the sum of the costs
** of all sub-scans required by the OR-scan. However, due to rounding
** errors, it may be that the cost of the OR-scan is equal to its
** most expensive sub-scan. Add the smallest possible penalty
** (equivalent to multiplying the cost by 1.07) to ensure that
** this does not happen. Otherwise, for WHERE clauses such as the
** following where there is an index on "y":
**
** WHERE likelihood(x=?, 0.99) OR y=?
**
** the planner may elect to "OR" together a full-table scan and an
** index lookup. And other similarly odd results. */
pNew->rRun = sSum.a[i].rRun + 1;
pNew->nOut = sSum.a[i].nOut;
pNew->prereq = sSum.a[i].prereq;
rc = whereLoopInsert(pBuilder, pNew);
}
WHERETRACE(0x200, ("End processing OR-clause %p\n", pTerm));
}
}
return rc;
}
/*
** Add all WhereLoop objects for all tables
*/
static int whereLoopAddAll(WhereLoopBuilder *pBuilder){
WhereInfo *pWInfo = pBuilder->pWInfo;
Bitmask mExtra = 0;
Bitmask mPrior = 0;
int iTab;
SrcList *pTabList = pWInfo->pTabList;
struct SrcList_item *pItem;
struct SrcList_item *pEnd = &pTabList->a[pWInfo->nLevel];
sqlite3 *db = pWInfo->pParse->db;
int rc = SQLITE_OK;
WhereLoop *pNew;
u8 priorJointype = 0;
/* Loop over the tables in the join, from left to right */
pNew = pBuilder->pNew;
whereLoopInit(pNew);
for(iTab=0, pItem=pTabList->a; pItem<pEnd; iTab++, pItem++){
Bitmask mUnusable = 0;
pNew->iTab = iTab;
pNew->maskSelf = sqlite3WhereGetMask(&pWInfo->sMaskSet, pItem->iCursor);
if( ((pItem->fg.jointype|priorJointype) & (JT_LEFT|JT_CROSS))!=0 ){
/* This condition is true when pItem is the FROM clause term on the
** right-hand-side of a LEFT or CROSS JOIN. */
mExtra = mPrior;
}
priorJointype = pItem->fg.jointype;
if( IsVirtual(pItem->pTab) ){
struct SrcList_item *p;
for(p=&pItem[1]; p<pEnd; p++){
if( mUnusable || (p->fg.jointype & (JT_LEFT|JT_CROSS)) ){
mUnusable |= sqlite3WhereGetMask(&pWInfo->sMaskSet, p->iCursor);
}
}
rc = whereLoopAddVirtual(pBuilder, mExtra, mUnusable);
}else{
rc = whereLoopAddBtree(pBuilder, mExtra);
}
if( rc==SQLITE_OK ){
rc = whereLoopAddOr(pBuilder, mExtra, mUnusable);
}
mPrior |= pNew->maskSelf;
if( rc || db->mallocFailed ) break;
}
whereLoopClear(db, pNew);
return rc;
}
/*
** Examine a WherePath (with the addition of the extra WhereLoop of the 5th
** parameters) to see if it outputs rows in the requested ORDER BY
** (or GROUP BY) without requiring a separate sort operation. Return N:
**
** N>0: N terms of the ORDER BY clause are satisfied
** N==0: No terms of the ORDER BY clause are satisfied
** N<0: Unknown yet how many terms of ORDER BY might be satisfied.
**
** Note that processing for WHERE_GROUPBY and WHERE_DISTINCTBY is not as
** strict. With GROUP BY and DISTINCT the only requirement is that
** equivalent rows appear immediately adjacent to one another. GROUP BY
** and DISTINCT do not require rows to appear in any particular order as long
** as equivalent rows are grouped together. Thus for GROUP BY and DISTINCT
** the pOrderBy terms can be matched in any order. With ORDER BY, the
** pOrderBy terms must be matched in strict left-to-right order.
*/
static i8 wherePathSatisfiesOrderBy(
WhereInfo *pWInfo, /* The WHERE clause */
ExprList *pOrderBy, /* ORDER BY or GROUP BY or DISTINCT clause to check */
WherePath *pPath, /* The WherePath to check */
u16 wctrlFlags, /* Might contain WHERE_GROUPBY or WHERE_DISTINCTBY */
u16 nLoop, /* Number of entries in pPath->aLoop[] */
WhereLoop *pLast, /* Add this WhereLoop to the end of pPath->aLoop[] */
Bitmask *pRevMask /* OUT: Mask of WhereLoops to run in reverse order */
){
u8 revSet; /* True if rev is known */
u8 rev; /* Composite sort order */
u8 revIdx; /* Index sort order */
u8 isOrderDistinct; /* All prior WhereLoops are order-distinct */
u8 distinctColumns; /* True if the loop has UNIQUE NOT NULL columns */
u8 isMatch; /* iColumn matches a term of the ORDER BY clause */
u16 nKeyCol; /* Number of key columns in pIndex */
u16 nColumn; /* Total number of ordered columns in the index */
u16 nOrderBy; /* Number terms in the ORDER BY clause */
int iLoop; /* Index of WhereLoop in pPath being processed */
int i, j; /* Loop counters */
int iCur; /* Cursor number for current WhereLoop */
int iColumn; /* A column number within table iCur */
WhereLoop *pLoop = 0; /* Current WhereLoop being processed. */
WhereTerm *pTerm; /* A single term of the WHERE clause */
Expr *pOBExpr; /* An expression from the ORDER BY clause */
CollSeq *pColl; /* COLLATE function from an ORDER BY clause term */
Index *pIndex; /* The index associated with pLoop */
sqlite3 *db = pWInfo->pParse->db; /* Database connection */
Bitmask obSat = 0; /* Mask of ORDER BY terms satisfied so far */
Bitmask obDone; /* Mask of all ORDER BY terms */
Bitmask orderDistinctMask; /* Mask of all well-ordered loops */
Bitmask ready; /* Mask of inner loops */
/*
** We say the WhereLoop is "one-row" if it generates no more than one
** row of output. A WhereLoop is one-row if all of the following are true:
** (a) All index columns match with WHERE_COLUMN_EQ.
** (b) The index is unique
** Any WhereLoop with an WHERE_COLUMN_EQ constraint on the rowid is one-row.
** Every one-row WhereLoop will have the WHERE_ONEROW bit set in wsFlags.
**
** We say the WhereLoop is "order-distinct" if the set of columns from
** that WhereLoop that are in the ORDER BY clause are different for every
** row of the WhereLoop. Every one-row WhereLoop is automatically
** order-distinct. A WhereLoop that has no columns in the ORDER BY clause
** is not order-distinct. To be order-distinct is not quite the same as being
** UNIQUE since a UNIQUE column or index can have multiple rows that
** are NULL and NULL values are equivalent for the purpose of order-distinct.
** To be order-distinct, the columns must be UNIQUE and NOT NULL.
**
** The rowid for a table is always UNIQUE and NOT NULL so whenever the
** rowid appears in the ORDER BY clause, the corresponding WhereLoop is
** automatically order-distinct.
*/
assert( pOrderBy!=0 );
if( nLoop && OptimizationDisabled(db, SQLITE_OrderByIdxJoin) ) return 0;
nOrderBy = pOrderBy->nExpr;
testcase( nOrderBy==BMS-1 );
if( nOrderBy>BMS-1 ) return 0; /* Cannot optimize overly large ORDER BYs */
isOrderDistinct = 1;
obDone = MASKBIT(nOrderBy)-1;
orderDistinctMask = 0;
ready = 0;
for(iLoop=0; isOrderDistinct && obSat<obDone && iLoop<=nLoop; iLoop++){
if( iLoop>0 ) ready |= pLoop->maskSelf;
pLoop = iLoop<nLoop ? pPath->aLoop[iLoop] : pLast;
if( pLoop->wsFlags & WHERE_VIRTUALTABLE ){
if( pLoop->u.vtab.isOrdered ) obSat = obDone;
break;
}
iCur = pWInfo->pTabList->a[pLoop->iTab].iCursor;
/* Mark off any ORDER BY term X that is a column in the table of
** the current loop for which there is term in the WHERE
** clause of the form X IS NULL or X=? that reference only outer
** loops.
*/
for(i=0; i<nOrderBy; i++){
if( MASKBIT(i) & obSat ) continue;
pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
if( pOBExpr->op!=TK_COLUMN ) continue;
if( pOBExpr->iTable!=iCur ) continue;
pTerm = sqlite3WhereFindTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn,
~ready, WO_EQ|WO_ISNULL|WO_IS, 0);
if( pTerm==0 ) continue;
if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 && pOBExpr->iColumn>=0 ){
const char *z1, *z2;
pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
if( !pColl ) pColl = db->pDfltColl;
z1 = pColl->zName;
pColl = sqlite3ExprCollSeq(pWInfo->pParse, pTerm->pExpr);
if( !pColl ) pColl = db->pDfltColl;
z2 = pColl->zName;
if( sqlite3StrICmp(z1, z2)!=0 ) continue;
testcase( pTerm->pExpr->op==TK_IS );
}
obSat |= MASKBIT(i);
}
if( (pLoop->wsFlags & WHERE_ONEROW)==0 ){
if( pLoop->wsFlags & WHERE_IPK ){
pIndex = 0;
nKeyCol = 0;
nColumn = 1;
}else if( (pIndex = pLoop->u.btree.pIndex)==0 || pIndex->bUnordered ){
return 0;
}else{
nKeyCol = pIndex->nKeyCol;
nColumn = pIndex->nColumn;
assert( nColumn==nKeyCol+1 || !HasRowid(pIndex->pTable) );
assert( pIndex->aiColumn[nColumn-1]==XN_ROWID
|| !HasRowid(pIndex->pTable));
isOrderDistinct = IsUniqueIndex(pIndex);
}
/* Loop through all columns of the index and deal with the ones
** that are not constrained by == or IN.
*/
rev = revSet = 0;
distinctColumns = 0;
for(j=0; j<nColumn; j++){
u8 bOnce; /* True to run the ORDER BY search loop */
/* Skip over == and IS NULL terms */
if( j<pLoop->u.btree.nEq
&& pLoop->nSkip==0
&& ((i = pLoop->aLTerm[j]->eOperator) & (WO_EQ|WO_ISNULL|WO_IS))!=0
){
if( i & WO_ISNULL ){
testcase( isOrderDistinct );
isOrderDistinct = 0;
}
continue;
}
/* Get the column number in the table (iColumn) and sort order
** (revIdx) for the j-th column of the index.
*/
if( pIndex ){
iColumn = pIndex->aiColumn[j];
revIdx = pIndex->aSortOrder[j];
if( iColumn==pIndex->pTable->iPKey ) iColumn = -1;
}else{
iColumn = XN_ROWID;
revIdx = 0;
}
/* An unconstrained column that might be NULL means that this
** WhereLoop is not well-ordered
*/
if( isOrderDistinct
&& iColumn>=0
&& j>=pLoop->u.btree.nEq
&& pIndex->pTable->aCol[iColumn].notNull==0
){
isOrderDistinct = 0;
}
/* Find the ORDER BY term that corresponds to the j-th column
** of the index and mark that ORDER BY term off
*/
bOnce = 1;
isMatch = 0;
for(i=0; bOnce && i<nOrderBy; i++){
if( MASKBIT(i) & obSat ) continue;
pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
testcase( wctrlFlags & WHERE_GROUPBY );
testcase( wctrlFlags & WHERE_DISTINCTBY );
if( (wctrlFlags & (WHERE_GROUPBY|WHERE_DISTINCTBY))==0 ) bOnce = 0;
if( iColumn>=(-1) ){
if( pOBExpr->op!=TK_COLUMN ) continue;
if( pOBExpr->iTable!=iCur ) continue;
if( pOBExpr->iColumn!=iColumn ) continue;
}else{
if( sqlite3ExprCompare(pOBExpr,pIndex->aColExpr->a[j].pExpr,iCur) ){
continue;
}
}
if( iColumn>=0 ){
pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
if( !pColl ) pColl = db->pDfltColl;
if( sqlite3StrICmp(pColl->zName, pIndex->azColl[j])!=0 ) continue;
}
isMatch = 1;
break;
}
if( isMatch && (wctrlFlags & WHERE_GROUPBY)==0 ){
/* Make sure the sort order is compatible in an ORDER BY clause.
** Sort order is irrelevant for a GROUP BY clause. */
if( revSet ){
if( (rev ^ revIdx)!=pOrderBy->a[i].sortOrder ) isMatch = 0;
}else{
rev = revIdx ^ pOrderBy->a[i].sortOrder;
if( rev ) *pRevMask |= MASKBIT(iLoop);
revSet = 1;
}
}
if( isMatch ){
if( iColumn<0 ){
testcase( distinctColumns==0 );
distinctColumns = 1;
}
obSat |= MASKBIT(i);
}else{
/* No match found */
if( j==0 || j<nKeyCol ){
testcase( isOrderDistinct!=0 );
isOrderDistinct = 0;
}
break;
}
} /* end Loop over all index columns */
if( distinctColumns ){
testcase( isOrderDistinct==0 );
isOrderDistinct = 1;
}
} /* end-if not one-row */
/* Mark off any other ORDER BY terms that reference pLoop */
if( isOrderDistinct ){
orderDistinctMask |= pLoop->maskSelf;
for(i=0; i<nOrderBy; i++){
Expr *p;
Bitmask mTerm;
if( MASKBIT(i) & obSat ) continue;
p = pOrderBy->a[i].pExpr;
mTerm = sqlite3WhereExprUsage(&pWInfo->sMaskSet,p);
if( mTerm==0 && !sqlite3ExprIsConstant(p) ) continue;
if( (mTerm&~orderDistinctMask)==0 ){
obSat |= MASKBIT(i);
}
}
}
} /* End the loop over all WhereLoops from outer-most down to inner-most */
if( obSat==obDone ) return (i8)nOrderBy;
if( !isOrderDistinct ){
for(i=nOrderBy-1; i>0; i--){
Bitmask m = MASKBIT(i) - 1;
if( (obSat&m)==m ) return i;
}
return 0;
}
return -1;
}
/*
** If the WHERE_GROUPBY flag is set in the mask passed to sqlite3WhereBegin(),
** the planner assumes that the specified pOrderBy list is actually a GROUP
** BY clause - and so any order that groups rows as required satisfies the
** request.
**
** Normally, in this case it is not possible for the caller to determine
** whether or not the rows are really being delivered in sorted order, or
** just in some other order that provides the required grouping. However,
** if the WHERE_SORTBYGROUP flag is also passed to sqlite3WhereBegin(), then
** this function may be called on the returned WhereInfo object. It returns
** true if the rows really will be sorted in the specified order, or false
** otherwise.
**
** For example, assuming:
**
** CREATE INDEX i1 ON t1(x, Y);
**
** then
**
** SELECT * FROM t1 GROUP BY x,y ORDER BY x,y; -- IsSorted()==1
** SELECT * FROM t1 GROUP BY y,x ORDER BY y,x; -- IsSorted()==0
*/
int sqlite3WhereIsSorted(WhereInfo *pWInfo){
assert( pWInfo->wctrlFlags & WHERE_GROUPBY );
assert( pWInfo->wctrlFlags & WHERE_SORTBYGROUP );
return pWInfo->sorted;
}
#ifdef WHERETRACE_ENABLED
/* For debugging use only: */
static const char *wherePathName(WherePath *pPath, int nLoop, WhereLoop *pLast){
static char zName[65];
int i;
for(i=0; i<nLoop; i++){ zName[i] = pPath->aLoop[i]->cId; }
if( pLast ) zName[i++] = pLast->cId;
zName[i] = 0;
return zName;
}
#endif
/*
** Return the cost of sorting nRow rows, assuming that the keys have
** nOrderby columns and that the first nSorted columns are already in
** order.
*/
static LogEst whereSortingCost(
WhereInfo *pWInfo,
LogEst nRow,
int nOrderBy,
int nSorted
){
/* TUNING: Estimated cost of a full external sort, where N is
** the number of rows to sort is:
**
** cost = (3.0 * N * log(N)).
**
** Or, if the order-by clause has X terms but only the last Y
** terms are out of order, then block-sorting will reduce the
** sorting cost to:
**
** cost = (3.0 * N * log(N)) * (Y/X)
**
** The (Y/X) term is implemented using stack variable rScale
** below. */
LogEst rScale, rSortCost;
assert( nOrderBy>0 && 66==sqlite3LogEst(100) );
rScale = sqlite3LogEst((nOrderBy-nSorted)*100/nOrderBy) - 66;
rSortCost = nRow + estLog(nRow) + rScale + 16;
/* TUNING: The cost of implementing DISTINCT using a B-TREE is
** similar but with a larger constant of proportionality.
** Multiply by an additional factor of 3.0. */
if( pWInfo->wctrlFlags & WHERE_WANT_DISTINCT ){
rSortCost += 16;
}
return rSortCost;
}
/*
** Given the list of WhereLoop objects at pWInfo->pLoops, this routine
** attempts to find the lowest cost path that visits each WhereLoop
** once. This path is then loaded into the pWInfo->a[].pWLoop fields.
**
** Assume that the total number of output rows that will need to be sorted
** will be nRowEst (in the 10*log2 representation). Or, ignore sorting
** costs if nRowEst==0.
**
** Return SQLITE_OK on success or SQLITE_NOMEM of a memory allocation
** error occurs.
*/
static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){
int mxChoice; /* Maximum number of simultaneous paths tracked */
int nLoop; /* Number of terms in the join */
Parse *pParse; /* Parsing context */
sqlite3 *db; /* The database connection */
int iLoop; /* Loop counter over the terms of the join */
int ii, jj; /* Loop counters */
int mxI = 0; /* Index of next entry to replace */
int nOrderBy; /* Number of ORDER BY clause terms */
LogEst mxCost = 0; /* Maximum cost of a set of paths */
LogEst mxUnsorted = 0; /* Maximum unsorted cost of a set of path */
int nTo, nFrom; /* Number of valid entries in aTo[] and aFrom[] */
WherePath *aFrom; /* All nFrom paths at the previous level */
WherePath *aTo; /* The nTo best paths at the current level */
WherePath *pFrom; /* An element of aFrom[] that we are working on */
WherePath *pTo; /* An element of aTo[] that we are working on */
WhereLoop *pWLoop; /* One of the WhereLoop objects */
WhereLoop **pX; /* Used to divy up the pSpace memory */
LogEst *aSortCost = 0; /* Sorting and partial sorting costs */
char *pSpace; /* Temporary memory used by this routine */
int nSpace; /* Bytes of space allocated at pSpace */
pParse = pWInfo->pParse;
db = pParse->db;
nLoop = pWInfo->nLevel;
/* TUNING: For simple queries, only the best path is tracked.
** For 2-way joins, the 5 best paths are followed.
** For joins of 3 or more tables, track the 10 best paths */
mxChoice = (nLoop<=1) ? 1 : (nLoop==2 ? 5 : 10);
assert( nLoop<=pWInfo->pTabList->nSrc );
WHERETRACE(0x002, ("---- begin solver. (nRowEst=%d)\n", nRowEst));
/* If nRowEst is zero and there is an ORDER BY clause, ignore it. In this
** case the purpose of this call is to estimate the number of rows returned
** by the overall query. Once this estimate has been obtained, the caller
** will invoke this function a second time, passing the estimate as the
** nRowEst parameter. */
if( pWInfo->pOrderBy==0 || nRowEst==0 ){
nOrderBy = 0;
}else{
nOrderBy = pWInfo->pOrderBy->nExpr;
}
/* Allocate and initialize space for aTo, aFrom and aSortCost[] */
nSpace = (sizeof(WherePath)+sizeof(WhereLoop*)*nLoop)*mxChoice*2;
nSpace += sizeof(LogEst) * nOrderBy;
pSpace = sqlite3DbMallocRaw(db, nSpace);
if( pSpace==0 ) return SQLITE_NOMEM;
aTo = (WherePath*)pSpace;
aFrom = aTo+mxChoice;
memset(aFrom, 0, sizeof(aFrom[0]));
pX = (WhereLoop**)(aFrom+mxChoice);
for(ii=mxChoice*2, pFrom=aTo; ii>0; ii--, pFrom++, pX += nLoop){
pFrom->aLoop = pX;
}
if( nOrderBy ){
/* If there is an ORDER BY clause and it is not being ignored, set up
** space for the aSortCost[] array. Each element of the aSortCost array
** is either zero - meaning it has not yet been initialized - or the
** cost of sorting nRowEst rows of data where the first X terms of
** the ORDER BY clause are already in order, where X is the array
** index. */
aSortCost = (LogEst*)pX;
memset(aSortCost, 0, sizeof(LogEst) * nOrderBy);
}
assert( aSortCost==0 || &pSpace[nSpace]==(char*)&aSortCost[nOrderBy] );
assert( aSortCost!=0 || &pSpace[nSpace]==(char*)pX );
/* Seed the search with a single WherePath containing zero WhereLoops.
**
** TUNING: Do not let the number of iterations go above 28. If the cost
** of computing an automatic index is not paid back within the first 28
** rows, then do not use the automatic index. */
aFrom[0].nRow = MIN(pParse->nQueryLoop, 48); assert( 48==sqlite3LogEst(28) );
nFrom = 1;
assert( aFrom[0].isOrdered==0 );
if( nOrderBy ){
/* If nLoop is zero, then there are no FROM terms in the query. Since
** in this case the query may return a maximum of one row, the results
** are already in the requested order. Set isOrdered to nOrderBy to
** indicate this. Or, if nLoop is greater than zero, set isOrdered to
** -1, indicating that the result set may or may not be ordered,
** depending on the loops added to the current plan. */
aFrom[0].isOrdered = nLoop>0 ? -1 : nOrderBy;
}
/* Compute successively longer WherePaths using the previous generation
** of WherePaths as the basis for the next. Keep track of the mxChoice
** best paths at each generation */
for(iLoop=0; iLoop<nLoop; iLoop++){
nTo = 0;
for(ii=0, pFrom=aFrom; ii<nFrom; ii++, pFrom++){
for(pWLoop=pWInfo->pLoops; pWLoop; pWLoop=pWLoop->pNextLoop){
LogEst nOut; /* Rows visited by (pFrom+pWLoop) */
LogEst rCost; /* Cost of path (pFrom+pWLoop) */
LogEst rUnsorted; /* Unsorted cost of (pFrom+pWLoop) */
i8 isOrdered = pFrom->isOrdered; /* isOrdered for (pFrom+pWLoop) */
Bitmask maskNew; /* Mask of src visited by (..) */
Bitmask revMask = 0; /* Mask of rev-order loops for (..) */
if( (pWLoop->prereq & ~pFrom->maskLoop)!=0 ) continue;
if( (pWLoop->maskSelf & pFrom->maskLoop)!=0 ) continue;
/* At this point, pWLoop is a candidate to be the next loop.
** Compute its cost */
rUnsorted = sqlite3LogEstAdd(pWLoop->rSetup,pWLoop->rRun + pFrom->nRow);
rUnsorted = sqlite3LogEstAdd(rUnsorted, pFrom->rUnsorted);
nOut = pFrom->nRow + pWLoop->nOut;
maskNew = pFrom->maskLoop | pWLoop->maskSelf;
if( isOrdered<0 ){
isOrdered = wherePathSatisfiesOrderBy(pWInfo,
pWInfo->pOrderBy, pFrom, pWInfo->wctrlFlags,
iLoop, pWLoop, &revMask);
}else{
revMask = pFrom->revLoop;
}
if( isOrdered>=0 && isOrdered<nOrderBy ){
if( aSortCost[isOrdered]==0 ){
aSortCost[isOrdered] = whereSortingCost(
pWInfo, nRowEst, nOrderBy, isOrdered
);
}
rCost = sqlite3LogEstAdd(rUnsorted, aSortCost[isOrdered]);
WHERETRACE(0x002,
("---- sort cost=%-3d (%d/%d) increases cost %3d to %-3d\n",
aSortCost[isOrdered], (nOrderBy-isOrdered), nOrderBy,
rUnsorted, rCost));
}else{
rCost = rUnsorted;
}
/* Check to see if pWLoop should be added to the set of
** mxChoice best-so-far paths.
**
** First look for an existing path among best-so-far paths
** that covers the same set of loops and has the same isOrdered
** setting as the current path candidate.
**
** The term "((pTo->isOrdered^isOrdered)&0x80)==0" is equivalent
** to (pTo->isOrdered==(-1))==(isOrdered==(-1))" for the range
** of legal values for isOrdered, -1..64.
*/
for(jj=0, pTo=aTo; jj<nTo; jj++, pTo++){
if( pTo->maskLoop==maskNew
&& ((pTo->isOrdered^isOrdered)&0x80)==0
){
testcase( jj==nTo-1 );
break;
}
}
if( jj>=nTo ){
/* None of the existing best-so-far paths match the candidate. */
if( nTo>=mxChoice
&& (rCost>mxCost || (rCost==mxCost && rUnsorted>=mxUnsorted))
){
/* The current candidate is no better than any of the mxChoice
** paths currently in the best-so-far buffer. So discard
** this candidate as not viable. */
#ifdef WHERETRACE_ENABLED /* 0x4 */
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf("Skip %s cost=%-3d,%3d order=%c\n",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
isOrdered>=0 ? isOrdered+'0' : '?');
}
#endif
continue;
}
/* If we reach this points it means that the new candidate path
** needs to be added to the set of best-so-far paths. */
if( nTo<mxChoice ){
/* Increase the size of the aTo set by one */
jj = nTo++;
}else{
/* New path replaces the prior worst to keep count below mxChoice */
jj = mxI;
}
pTo = &aTo[jj];
#ifdef WHERETRACE_ENABLED /* 0x4 */
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf("New %s cost=%-3d,%3d order=%c\n",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
isOrdered>=0 ? isOrdered+'0' : '?');
}
#endif
}else{
/* Control reaches here if best-so-far path pTo=aTo[jj] covers the
** same set of loops and has the sam isOrdered setting as the
** candidate path. Check to see if the candidate should replace
** pTo or if the candidate should be skipped */
if( pTo->rCost<rCost || (pTo->rCost==rCost && pTo->nRow<=nOut) ){
#ifdef WHERETRACE_ENABLED /* 0x4 */
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf(
"Skip %s cost=%-3d,%3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
isOrdered>=0 ? isOrdered+'0' : '?');
sqlite3DebugPrintf(" vs %s cost=%-3d,%d order=%c\n",
wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?');
}
#endif
/* Discard the candidate path from further consideration */
testcase( pTo->rCost==rCost );
continue;
}
testcase( pTo->rCost==rCost+1 );
/* Control reaches here if the candidate path is better than the
** pTo path. Replace pTo with the candidate. */
#ifdef WHERETRACE_ENABLED /* 0x4 */
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf(
"Update %s cost=%-3d,%3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
isOrdered>=0 ? isOrdered+'0' : '?');
sqlite3DebugPrintf(" was %s cost=%-3d,%3d order=%c\n",
wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?');
}
#endif
}
/* pWLoop is a winner. Add it to the set of best so far */
pTo->maskLoop = pFrom->maskLoop | pWLoop->maskSelf;
pTo->revLoop = revMask;
pTo->nRow = nOut;
pTo->rCost = rCost;
pTo->rUnsorted = rUnsorted;
pTo->isOrdered = isOrdered;
memcpy(pTo->aLoop, pFrom->aLoop, sizeof(WhereLoop*)*iLoop);
pTo->aLoop[iLoop] = pWLoop;
if( nTo>=mxChoice ){
mxI = 0;
mxCost = aTo[0].rCost;
mxUnsorted = aTo[0].nRow;
for(jj=1, pTo=&aTo[1]; jj<mxChoice; jj++, pTo++){
if( pTo->rCost>mxCost
|| (pTo->rCost==mxCost && pTo->rUnsorted>mxUnsorted)
){
mxCost = pTo->rCost;
mxUnsorted = pTo->rUnsorted;
mxI = jj;
}
}
}
}
}
#ifdef WHERETRACE_ENABLED /* >=2 */
if( sqlite3WhereTrace & 0x02 ){
sqlite3DebugPrintf("---- after round %d ----\n", iLoop);
for(ii=0, pTo=aTo; ii<nTo; ii++, pTo++){
sqlite3DebugPrintf(" %s cost=%-3d nrow=%-3d order=%c",
wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
pTo->isOrdered>=0 ? (pTo->isOrdered+'0') : '?');
if( pTo->isOrdered>0 ){
sqlite3DebugPrintf(" rev=0x%llx\n", pTo->revLoop);
}else{
sqlite3DebugPrintf("\n");
}
}
}
#endif
/* Swap the roles of aFrom and aTo for the next generation */
pFrom = aTo;
aTo = aFrom;
aFrom = pFrom;
nFrom = nTo;
}
if( nFrom==0 ){
sqlite3ErrorMsg(pParse, "no query solution");
sqlite3DbFree(db, pSpace);
return SQLITE_ERROR;
}
/* Find the lowest cost path. pFrom will be left pointing to that path */
pFrom = aFrom;
for(ii=1; ii<nFrom; ii++){
if( pFrom->rCost>aFrom[ii].rCost ) pFrom = &aFrom[ii];
}
assert( pWInfo->nLevel==nLoop );
/* Load the lowest cost path into pWInfo */
for(iLoop=0; iLoop<nLoop; iLoop++){
WhereLevel *pLevel = pWInfo->a + iLoop;
pLevel->pWLoop = pWLoop = pFrom->aLoop[iLoop];
pLevel->iFrom = pWLoop->iTab;
pLevel->iTabCur = pWInfo->pTabList->a[pLevel->iFrom].iCursor;
}
if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)!=0
&& (pWInfo->wctrlFlags & WHERE_DISTINCTBY)==0
&& pWInfo->eDistinct==WHERE_DISTINCT_NOOP
&& nRowEst
){
Bitmask notUsed;
int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pResultSet, pFrom,
WHERE_DISTINCTBY, nLoop-1, pFrom->aLoop[nLoop-1], &notUsed);
if( rc==pWInfo->pResultSet->nExpr ){
pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
}
}
if( pWInfo->pOrderBy ){
if( pWInfo->wctrlFlags & WHERE_DISTINCTBY ){
if( pFrom->isOrdered==pWInfo->pOrderBy->nExpr ){
pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
}
}else{
pWInfo->nOBSat = pFrom->isOrdered;
if( pWInfo->nOBSat<0 ) pWInfo->nOBSat = 0;
pWInfo->revMask = pFrom->revLoop;
}
if( (pWInfo->wctrlFlags & WHERE_SORTBYGROUP)
&& pWInfo->nOBSat==pWInfo->pOrderBy->nExpr && nLoop>0
){
Bitmask revMask = 0;
int nOrder = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy,
pFrom, 0, nLoop-1, pFrom->aLoop[nLoop-1], &revMask
);
assert( pWInfo->sorted==0 );
if( nOrder==pWInfo->pOrderBy->nExpr ){
pWInfo->sorted = 1;
pWInfo->revMask = revMask;
}
}
}
pWInfo->nRowOut = pFrom->nRow;
/* Free temporary memory and return success */
sqlite3DbFree(db, pSpace);
return SQLITE_OK;
}
/*
** Most queries use only a single table (they are not joins) and have
** simple == constraints against indexed fields. This routine attempts
** to plan those simple cases using much less ceremony than the
** general-purpose query planner, and thereby yield faster sqlite3_prepare()
** times for the common case.
**
** Return non-zero on success, if this query can be handled by this
** no-frills query planner. Return zero if this query needs the
** general-purpose query planner.
*/
static int whereShortCut(WhereLoopBuilder *pBuilder){
WhereInfo *pWInfo;
struct SrcList_item *pItem;
WhereClause *pWC;
WhereTerm *pTerm;
WhereLoop *pLoop;
int iCur;
int j;
Table *pTab;
Index *pIdx;
pWInfo = pBuilder->pWInfo;
if( pWInfo->wctrlFlags & WHERE_FORCE_TABLE ) return 0;
assert( pWInfo->pTabList->nSrc>=1 );
pItem = pWInfo->pTabList->a;
pTab = pItem->pTab;
if( IsVirtual(pTab) ) return 0;
if( pItem->fg.isIndexedBy ) return 0;
iCur = pItem->iCursor;
pWC = &pWInfo->sWC;
pLoop = pBuilder->pNew;
pLoop->wsFlags = 0;
pLoop->nSkip = 0;
pTerm = sqlite3WhereFindTerm(pWC, iCur, -1, 0, WO_EQ|WO_IS, 0);
if( pTerm ){
testcase( pTerm->eOperator & WO_IS );
pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_IPK|WHERE_ONEROW;
pLoop->aLTerm[0] = pTerm;
pLoop->nLTerm = 1;
pLoop->u.btree.nEq = 1;
/* TUNING: Cost of a rowid lookup is 10 */
pLoop->rRun = 33; /* 33==sqlite3LogEst(10) */
}else{
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
int opMask;
assert( pLoop->aLTermSpace==pLoop->aLTerm );
if( !IsUniqueIndex(pIdx)
|| pIdx->pPartIdxWhere!=0
|| pIdx->nKeyCol>ArraySize(pLoop->aLTermSpace)
) continue;
opMask = pIdx->uniqNotNull ? (WO_EQ|WO_IS) : WO_EQ;
for(j=0; j<pIdx->nKeyCol; j++){
pTerm = sqlite3WhereFindTerm(pWC, iCur, j, 0, opMask, pIdx);
if( pTerm==0 ) break;
testcase( pTerm->eOperator & WO_IS );
pLoop->aLTerm[j] = pTerm;
}
if( j!=pIdx->nKeyCol ) continue;
pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_ONEROW|WHERE_INDEXED;
if( pIdx->isCovering || (pItem->colUsed & ~columnsInIndex(pIdx))==0 ){
pLoop->wsFlags |= WHERE_IDX_ONLY;
}
pLoop->nLTerm = j;
pLoop->u.btree.nEq = j;
pLoop->u.btree.pIndex = pIdx;
/* TUNING: Cost of a unique index lookup is 15 */
pLoop->rRun = 39; /* 39==sqlite3LogEst(15) */
break;
}
}
if( pLoop->wsFlags ){
pLoop->nOut = (LogEst)1;
pWInfo->a[0].pWLoop = pLoop;
pLoop->maskSelf = sqlite3WhereGetMask(&pWInfo->sMaskSet, iCur);
pWInfo->a[0].iTabCur = iCur;
pWInfo->nRowOut = 1;
if( pWInfo->pOrderBy ) pWInfo->nOBSat = pWInfo->pOrderBy->nExpr;
if( pWInfo->wctrlFlags & WHERE_WANT_DISTINCT ){
pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
}
#ifdef SQLITE_DEBUG
pLoop->cId = '0';
#endif
return 1;
}
return 0;
}
/*
** 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
**
** pOrderBy is a pointer to the ORDER BY clause (or the GROUP BY clause
** if the WHERE_GROUPBY flag is set in wctrlFlags) 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 pOrderBy is NULL.
**
** The iIdxCur parameter is the cursor number of an index. If
** WHERE_ONETABLE_ONLY is set, iIdxCur is the cursor number of an index
** to use for OR clause processing. The WHERE clause should use this
** specific cursor. If WHERE_ONEPASS_DESIRED is set, then iIdxCur is
** the first cursor in an array of cursors for all indices. iIdxCur should
** be used to compute the appropriate cursor depending on which index is
** used.
*/
WhereInfo *sqlite3WhereBegin(
Parse *pParse, /* The parser context */
SrcList *pTabList, /* FROM clause: A list of all tables to be scanned */
Expr *pWhere, /* The WHERE clause */
ExprList *pOrderBy, /* An ORDER BY (or GROUP BY) clause, or NULL */
ExprList *pResultSet, /* Result set of the query */
u16 wctrlFlags, /* One of the WHERE_* flags defined in sqliteInt.h */
int iIdxCur /* If WHERE_ONETABLE_ONLY is set, index cursor number */
){
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 */
WhereLoopBuilder sWLB; /* The WhereLoop builder */
WhereMaskSet *pMaskSet; /* The expression mask set */
WhereLevel *pLevel; /* A single level in pWInfo->a[] */
WhereLoop *pLoop; /* Pointer to a single WhereLoop object */
int ii; /* Loop counter */
sqlite3 *db; /* Database connection */
int rc; /* Return code */
u8 bFordelete = 0;
assert( (wctrlFlags & WHERE_ONEPASS_MULTIROW)==0 || (
(wctrlFlags & WHERE_ONEPASS_DESIRED)!=0
&& (wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0
));
/* Variable initialization */
db = pParse->db;
memset(&sWLB, 0, sizeof(sWLB));
/* An ORDER/GROUP BY clause of more than 63 terms cannot be optimized */
testcase( pOrderBy && pOrderBy->nExpr==BMS-1 );
if( pOrderBy && pOrderBy->nExpr>=BMS ) pOrderBy = 0;
sWLB.pOrderBy = pOrderBy;
/* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via
** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */
if( OptimizationDisabled(db, SQLITE_DistinctOpt) ){
wctrlFlags &= ~WHERE_WANT_DISTINCT;
}
/* 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.
*/
nByteWInfo = ROUND8(sizeof(WhereInfo)+(nTabList-1)*sizeof(WhereLevel));
pWInfo = sqlite3DbMallocZero(db, nByteWInfo + sizeof(WhereLoop));
if( db->mallocFailed ){
sqlite3DbFree(db, pWInfo);
pWInfo = 0;
goto whereBeginError;
}
pWInfo->aiCurOnePass[0] = pWInfo->aiCurOnePass[1] = -1;
pWInfo->nLevel = nTabList;
pWInfo->pParse = pParse;
pWInfo->pTabList = pTabList;
pWInfo->pOrderBy = pOrderBy;
pWInfo->pResultSet = pResultSet;
pWInfo->iBreak = pWInfo->iContinue = sqlite3VdbeMakeLabel(v);
pWInfo->wctrlFlags = wctrlFlags;
pWInfo->savedNQueryLoop = pParse->nQueryLoop;
assert( pWInfo->eOnePass==ONEPASS_OFF ); /* ONEPASS defaults to OFF */
pMaskSet = &pWInfo->sMaskSet;
sWLB.pWInfo = pWInfo;
sWLB.pWC = &pWInfo->sWC;
sWLB.pNew = (WhereLoop*)(((char*)pWInfo)+nByteWInfo);
assert( EIGHT_BYTE_ALIGNMENT(sWLB.pNew) );
whereLoopInit(sWLB.pNew);
#ifdef SQLITE_DEBUG
sWLB.pNew->cId = '*';
#endif
/* Split the WHERE clause into separate subexpressions where each
** subexpression is separated by an AND operator.
*/
initMaskSet(pMaskSet);
sqlite3WhereClauseInit(&pWInfo->sWC, pWInfo);
sqlite3WhereSplit(&pWInfo->sWC, pWhere, TK_AND);
/* Special case: a WHERE clause that is constant. Evaluate the
** expression and either jump over all of the code or fall thru.
*/
for(ii=0; ii<sWLB.pWC->nTerm; ii++){
if( nTabList==0 || sqlite3ExprIsConstantNotJoin(sWLB.pWC->a[ii].pExpr) ){
sqlite3ExprIfFalse(pParse, sWLB.pWC->a[ii].pExpr, pWInfo->iBreak,
SQLITE_JUMPIFNULL);
sWLB.pWC->a[ii].wtFlags |= TERM_CODED;
}
}
/* Special case: No FROM clause
*/
if( nTabList==0 ){
if( pOrderBy ) pWInfo->nOBSat = pOrderBy->nExpr;
if( wctrlFlags & WHERE_WANT_DISTINCT ){
pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
}
}
/* Assign a bit from the bitmask to every term in the FROM clause.
**
** The N-th term of the FROM clause is assigned a bitmask of 1<<N.
**
** The rule of the previous sentence ensures thta if X is the bitmask for
** a table T, then X-1 is the bitmask for all other tables to the left of T.
** Knowing the bitmask for all tables to the left of a left join is
** important. Ticket #3015.
**
** 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.
*/
for(ii=0; ii<pTabList->nSrc; ii++){
createMask(pMaskSet, pTabList->a[ii].iCursor);
sqlite3WhereTabFuncArgs(pParse, &pTabList->a[ii], &pWInfo->sWC);
}
#ifdef SQLITE_DEBUG
for(ii=0; ii<pTabList->nSrc; ii++){
Bitmask m = sqlite3WhereGetMask(pMaskSet, pTabList->a[ii].iCursor);
assert( m==MASKBIT(ii) );
}
#endif
/* Analyze all of the subexpressions. */
sqlite3WhereExprAnalyze(pTabList, &pWInfo->sWC);
if( db->mallocFailed ) goto whereBeginError;
if( wctrlFlags & WHERE_WANT_DISTINCT ){
if( isDistinctRedundant(pParse, pTabList, &pWInfo->sWC, pResultSet) ){
/* The DISTINCT marking is pointless. Ignore it. */
pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
}else if( pOrderBy==0 ){
/* Try to ORDER BY the result set to make distinct processing easier */
pWInfo->wctrlFlags |= WHERE_DISTINCTBY;
pWInfo->pOrderBy = pResultSet;
}
}
/* Construct the WhereLoop objects */
WHERETRACE(0xffff,("*** Optimizer Start *** (wctrlFlags: 0x%x)\n",
wctrlFlags));
#if defined(WHERETRACE_ENABLED)
if( sqlite3WhereTrace & 0x100 ){ /* Display all terms of the WHERE clause */
int i;
for(i=0; i<sWLB.pWC->nTerm; i++){
whereTermPrint(&sWLB.pWC->a[i], i);
}
}
#endif
if( nTabList!=1 || whereShortCut(&sWLB)==0 ){
rc = whereLoopAddAll(&sWLB);
if( rc ) goto whereBeginError;
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace ){ /* Display all of the WhereLoop objects */
WhereLoop *p;
int i;
static const char zLabel[] = "0123456789abcdefghijklmnopqrstuvwyxz"
"ABCDEFGHIJKLMNOPQRSTUVWYXZ";
for(p=pWInfo->pLoops, i=0; p; p=p->pNextLoop, i++){
p->cId = zLabel[i%sizeof(zLabel)];
whereLoopPrint(p, sWLB.pWC);
}
}
#endif
wherePathSolver(pWInfo, 0);
if( db->mallocFailed ) goto whereBeginError;
if( pWInfo->pOrderBy ){
wherePathSolver(pWInfo, pWInfo->nRowOut+1);
if( db->mallocFailed ) goto whereBeginError;
}
}
if( pWInfo->pOrderBy==0 && (db->flags & SQLITE_ReverseOrder)!=0 ){
pWInfo->revMask = (Bitmask)(-1);
}
if( pParse->nErr || NEVER(db->mallocFailed) ){
goto whereBeginError;
}
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace ){
sqlite3DebugPrintf("---- Solution nRow=%d", pWInfo->nRowOut);
if( pWInfo->nOBSat>0 ){
sqlite3DebugPrintf(" ORDERBY=%d,0x%llx", pWInfo->nOBSat, pWInfo->revMask);
}
switch( pWInfo->eDistinct ){
case WHERE_DISTINCT_UNIQUE: {
sqlite3DebugPrintf(" DISTINCT=unique");
break;
}
case WHERE_DISTINCT_ORDERED: {
sqlite3DebugPrintf(" DISTINCT=ordered");
break;
}
case WHERE_DISTINCT_UNORDERED: {
sqlite3DebugPrintf(" DISTINCT=unordered");
break;
}
}
sqlite3DebugPrintf("\n");
for(ii=0; ii<pWInfo->nLevel; ii++){
whereLoopPrint(pWInfo->a[ii].pWLoop, sWLB.pWC);
}
}
#endif
/* Attempt to omit tables from the join that do not effect the result */
if( pWInfo->nLevel>=2
&& pResultSet!=0
&& OptimizationEnabled(db, SQLITE_OmitNoopJoin)
){
Bitmask tabUsed = sqlite3WhereExprListUsage(pMaskSet, pResultSet);
if( sWLB.pOrderBy ){
tabUsed |= sqlite3WhereExprListUsage(pMaskSet, sWLB.pOrderBy);
}
while( pWInfo->nLevel>=2 ){
WhereTerm *pTerm, *pEnd;
pLoop = pWInfo->a[pWInfo->nLevel-1].pWLoop;
if( (pWInfo->pTabList->a[pLoop->iTab].fg.jointype & JT_LEFT)==0 ) break;
if( (wctrlFlags & WHERE_WANT_DISTINCT)==0
&& (pLoop->wsFlags & WHERE_ONEROW)==0
){
break;
}
if( (tabUsed & pLoop->maskSelf)!=0 ) break;
pEnd = sWLB.pWC->a + sWLB.pWC->nTerm;
for(pTerm=sWLB.pWC->a; pTerm<pEnd; pTerm++){
if( (pTerm->prereqAll & pLoop->maskSelf)!=0
&& !ExprHasProperty(pTerm->pExpr, EP_FromJoin)
){
break;
}
}
if( pTerm<pEnd ) break;
WHERETRACE(0xffff, ("-> drop loop %c not used\n", pLoop->cId));
pWInfo->nLevel--;
nTabList--;
}
}
WHERETRACE(0xffff,("*** Optimizer Finished ***\n"));
pWInfo->pParse->nQueryLoop += pWInfo->nRowOut;
/* 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 constrains
** the statement to update or delete a single row.
*/
assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 );
if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 ){
int wsFlags = pWInfo->a[0].pWLoop->wsFlags;
int bOnerow = (wsFlags & WHERE_ONEROW)!=0;
if( bOnerow || ( (wctrlFlags & WHERE_ONEPASS_MULTIROW)
&& 0==(wsFlags & WHERE_VIRTUALTABLE)
)){
pWInfo->eOnePass = bOnerow ? ONEPASS_SINGLE : ONEPASS_MULTI;
if( HasRowid(pTabList->a[0].pTab) && (wsFlags & WHERE_IDX_ONLY) ){
if( wctrlFlags & WHERE_ONEPASS_MULTIROW ){
bFordelete = OPFLAG_FORDELETE;
}
pWInfo->a[0].pWLoop->wsFlags = (wsFlags & ~WHERE_IDX_ONLY);
}
}
}
/* Open all tables in the pTabList and any indices selected for
** searching those tables.
*/
for(ii=0, pLevel=pWInfo->a; ii<nTabList; ii++, pLevel++){
Table *pTab; /* Table to open */
int iDb; /* Index of database containing table/index */
struct SrcList_item *pTabItem;
pTabItem = &pTabList->a[pLevel->iFrom];
pTab = pTabItem->pTab;
iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
pLoop = pLevel->pWLoop;
if( (pTab->tabFlags & TF_Ephemeral)!=0 || pTab->pSelect ){
/* Do nothing */
}else
#ifndef SQLITE_OMIT_VIRTUALTABLE
if( (pLoop->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 if( IsVirtual(pTab) ){
/* noop */
}else
#endif
if( (pLoop->wsFlags & WHERE_IDX_ONLY)==0
&& (wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0 ){
int op = OP_OpenRead;
if( pWInfo->eOnePass!=ONEPASS_OFF ){
op = OP_OpenWrite;
pWInfo->aiCurOnePass[0] = pTabItem->iCursor;
};
sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op);
assert( pTabItem->iCursor==pLevel->iTabCur );
testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS-1 );
testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS );
if( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol<BMS && HasRowid(pTab) ){
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 );
}
#ifdef SQLITE_ENABLE_CURSOR_HINTS
if( pLoop->u.btree.pIndex!=0 ){
sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ|bFordelete);
}else
#endif
{
sqlite3VdbeChangeP5(v, bFordelete);
}
#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, pTabItem->iCursor, 0, 0,
(const u8*)&pTabItem->colUsed, P4_INT64);
#endif
}else{
sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
}
if( pLoop->wsFlags & WHERE_INDEXED ){
Index *pIx = pLoop->u.btree.pIndex;
int iIndexCur;
int op = OP_OpenRead;
/* iIdxCur is always set if to a positive value if ONEPASS is possible */
assert( iIdxCur!=0 || (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 );
if( !HasRowid(pTab) && IsPrimaryKeyIndex(pIx)
&& (wctrlFlags & WHERE_ONETABLE_ONLY)!=0
){
/* This is one term of an OR-optimization using the PRIMARY KEY of a
** WITHOUT ROWID table. No need for a separate index */
iIndexCur = pLevel->iTabCur;
op = 0;
}else if( pWInfo->eOnePass!=ONEPASS_OFF ){
Index *pJ = pTabItem->pTab->pIndex;
iIndexCur = iIdxCur;
assert( wctrlFlags & WHERE_ONEPASS_DESIRED );
while( ALWAYS(pJ) && pJ!=pIx ){
iIndexCur++;
pJ = pJ->pNext;
}
op = OP_OpenWrite;
pWInfo->aiCurOnePass[1] = iIndexCur;
}else if( iIdxCur && (wctrlFlags & WHERE_ONETABLE_ONLY)!=0 ){
iIndexCur = iIdxCur;
if( wctrlFlags & WHERE_REOPEN_IDX ) op = OP_ReopenIdx;
}else{
iIndexCur = pParse->nTab++;
}
pLevel->iIdxCur = iIndexCur;
assert( pIx->pSchema==pTab->pSchema );
assert( iIndexCur>=0 );
if( op ){
sqlite3VdbeAddOp3(v, op, iIndexCur, pIx->tnum, iDb);
sqlite3VdbeSetP4KeyInfo(pParse, pIx);
if( (pLoop->wsFlags & WHERE_CONSTRAINT)!=0
&& (pLoop->wsFlags & (WHERE_COLUMN_RANGE|WHERE_SKIPSCAN))==0
&& (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0
){
sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ); /* Hint to COMDB2 */
}
VdbeComment((v, "%s", pIx->zName));
#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
{
u64 colUsed = 0;
int ii, jj;
for(ii=0; ii<pIx->nColumn; ii++){
jj = pIx->aiColumn[ii];
if( jj<0 ) continue;
if( jj>63 ) jj = 63;
if( (pTabItem->colUsed & MASKBIT(jj))==0 ) continue;
colUsed |= ((u64)1)<<(ii<63 ? ii : 63);
}
sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, iIndexCur, 0, 0,
(u8*)&colUsed, P4_INT64);
}
#endif /* SQLITE_ENABLE_COLUMN_USED_MASK */
}
}
if( iDb>=0 ) sqlite3CodeVerifySchema(pParse, iDb);
}
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(ii=0; ii<nTabList; ii++){
int addrExplain;
int wsFlags;
pLevel = &pWInfo->a[ii];
wsFlags = pLevel->pWLoop->wsFlags;
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
if( (pLevel->pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 ){
constructAutomaticIndex(pParse, &pWInfo->sWC,
&pTabList->a[pLevel->iFrom], notReady, pLevel);
if( db->mallocFailed ) goto whereBeginError;
}
#endif
addrExplain = sqlite3WhereExplainOneScan(
pParse, pTabList, pLevel, ii, pLevel->iFrom, wctrlFlags
);
pLevel->addrBody = sqlite3VdbeCurrentAddr(v);
notReady = sqlite3WhereCodeOneLoopStart(pWInfo, ii, notReady);
pWInfo->iContinue = pLevel->addrCont;
if( (wsFlags&WHERE_MULTI_OR)==0 && (wctrlFlags&WHERE_ONETABLE_ONLY)==0 ){
sqlite3WhereAddScanStatus(v, pTabList, pLevel, addrExplain);
}
}
/* Done. */
VdbeModuleComment((v, "Begin WHERE-core"));
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;
WhereLoop *pLoop;
SrcList *pTabList = pWInfo->pTabList;
sqlite3 *db = pParse->db;
/* Generate loop termination code.
*/
VdbeModuleComment((v, "End WHERE-core"));
sqlite3ExprCacheClear(pParse);
for(i=pWInfo->nLevel-1; i>=0; i--){
int addr;
pLevel = &pWInfo->a[i];
pLoop = pLevel->pWLoop;
sqlite3VdbeResolveLabel(v, pLevel->addrCont);
if( pLevel->op!=OP_Noop ){
sqlite3VdbeAddOp3(v, pLevel->op, pLevel->p1, pLevel->p2, pLevel->p3);
sqlite3VdbeChangeP5(v, pLevel->p5);
VdbeCoverage(v);
VdbeCoverageIf(v, pLevel->op==OP_Next);
VdbeCoverageIf(v, pLevel->op==OP_Prev);
VdbeCoverageIf(v, pLevel->op==OP_VNext);
}
if( pLoop->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, pIn->eEndLoopOp, pIn->iCur, pIn->addrInTop);
VdbeCoverage(v);
VdbeCoverageIf(v, pIn->eEndLoopOp==OP_PrevIfOpen);
VdbeCoverageIf(v, pIn->eEndLoopOp==OP_NextIfOpen);
sqlite3VdbeJumpHere(v, pIn->addrInTop-1);
}
}
sqlite3VdbeResolveLabel(v, pLevel->addrBrk);
if( pLevel->addrSkip ){
sqlite3VdbeGoto(v, pLevel->addrSkip);
VdbeComment((v, "next skip-scan on %s", pLoop->u.btree.pIndex->zName));
sqlite3VdbeJumpHere(v, pLevel->addrSkip);
sqlite3VdbeJumpHere(v, pLevel->addrSkip-2);
}
#ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
if( pLevel->addrLikeRep ){
int op;
if( sqlite3VdbeGetOp(v, pLevel->addrLikeRep-1)->p1 ){
op = OP_DecrJumpZero;
}else{
op = OP_JumpZeroIncr;
}
sqlite3VdbeAddOp2(v, op, pLevel->iLikeRepCntr, pLevel->addrLikeRep);
VdbeCoverage(v);
}
#endif
if( pLevel->iLeftJoin ){
addr = sqlite3VdbeAddOp1(v, OP_IfPos, pLevel->iLeftJoin); VdbeCoverage(v);
assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0
|| (pLoop->wsFlags & WHERE_INDEXED)!=0 );
if( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 ){
sqlite3VdbeAddOp1(v, OP_NullRow, pTabList->a[i].iCursor);
}
if( pLoop->wsFlags & WHERE_INDEXED ){
sqlite3VdbeAddOp1(v, OP_NullRow, pLevel->iIdxCur);
}
if( pLevel->op==OP_Return ){
sqlite3VdbeAddOp2(v, OP_Gosub, pLevel->p1, pLevel->addrFirst);
}else{
sqlite3VdbeGoto(v, pLevel->addrFirst);
}
sqlite3VdbeJumpHere(v, addr);
}
VdbeModuleComment((v, "End WHERE-loop%d: %s", i,
pWInfo->pTabList->a[pLevel->iFrom].pTab->zName));
}
/* The "break" point is here, just past the end of the outer loop.
** Set it.
*/
sqlite3VdbeResolveLabel(v, pWInfo->iBreak);
assert( pWInfo->nLevel<=pTabList->nSrc );
for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){
int k, last;
VdbeOp *pOp;
Index *pIdx = 0;
struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom];
Table *pTab = pTabItem->pTab;
assert( pTab!=0 );
pLoop = pLevel->pWLoop;
/* For a co-routine, change all OP_Column references to the table of
** the co-routine into OP_Copy of result contained in a register.
** OP_Rowid becomes OP_Null.
*/
if( pTabItem->fg.viaCoroutine && !db->mallocFailed ){
translateColumnToCopy(v, pLevel->addrBody, pLevel->iTabCur,
pTabItem->regResult, 0);
continue;
}
/* Close all of the cursors that were opened by sqlite3WhereBegin.
** Except, do not close cursors that will be reused by the OR optimization
** (WHERE_OMIT_OPEN_CLOSE). And do not close the OP_OpenWrite cursors
** created for the ONEPASS optimization.
*/
if( (pTab->tabFlags & TF_Ephemeral)==0
&& pTab->pSelect==0
&& (pWInfo->wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0
){
int ws = pLoop->wsFlags;
if( pWInfo->eOnePass==ONEPASS_OFF && (ws & WHERE_IDX_ONLY)==0 ){
sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
}
if( (ws & WHERE_INDEXED)!=0
&& (ws & (WHERE_IPK|WHERE_AUTO_INDEX))==0
&& pLevel->iIdxCur!=pWInfo->aiCurOnePass[1]
){
sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur);
}
}
/* If this scan uses an index, make VDBE code substitutions to read data
** from the index instead of from the table where possible. In some cases
** this optimization prevents the table from ever being read, which can
** yield a significant performance boost.
**
** 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( pLoop->wsFlags & (WHERE_INDEXED|WHERE_IDX_ONLY) ){
pIdx = pLoop->u.btree.pIndex;
}else if( pLoop->wsFlags & WHERE_MULTI_OR ){
pIdx = pLevel->u.pCovidx;
}
if( pIdx
&& (pWInfo->eOnePass==ONEPASS_OFF || !HasRowid(pIdx->pTable))
&& !db->mallocFailed
){
last = sqlite3VdbeCurrentAddr(v);
k = pLevel->addrBody;
pOp = sqlite3VdbeGetOp(v, k);
for(; k<last; k++, pOp++){
if( pOp->p1!=pLevel->iTabCur ) continue;
if( pOp->opcode==OP_Column ){
int x = pOp->p2;
assert( pIdx->pTable==pTab );
if( !HasRowid(pTab) ){
Index *pPk = sqlite3PrimaryKeyIndex(pTab);
x = pPk->aiColumn[x];
assert( x>=0 );
}
x = sqlite3ColumnOfIndex(pIdx, x);
if( x>=0 ){
pOp->p2 = x;
pOp->p1 = pLevel->iIdxCur;
}
assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 || x>=0 );
}else if( pOp->opcode==OP_Rowid ){
pOp->p1 = pLevel->iIdxCur;
pOp->opcode = OP_IdxRowid;
}
}
}
}
/* Final cleanup
*/
pParse->nQueryLoop = pWInfo->savedNQueryLoop;
whereInfoFree(db, pWInfo);
return;
}