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** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements. This module is reponsible 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".
**
** $Id: where.c,v 1.122 2004/12/18 18:40:27 drh Exp $
** $Id: where.c,v 1.123 2004/12/19 00:11:35 drh Exp $
*/
#include "sqliteInt.h"
/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause. Each WHERE
** clause subexpression is separated from the others by an AND operator.
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SWAP(unsigned, pInfo->prereqLeft, pInfo->prereqRight);
SWAP(short int, pInfo->idxLeft, pInfo->idxRight);
}
}
}
/*
** pOrderBy is an ORDER BY clause from a SELECT statement. pTab is the
** left-most table in the FROM clause of that same SELECT statement and
** the table has a cursor number of "base".
**
** This routine attempts to find an index for pTab that generates the
** correct record sequence for the given ORDER BY clause. The return value
** is a pointer to an index that does the job. NULL is returned if the
** table has no index that will generate the correct sort order.
**
** If there are two or more indices that generate the correct sort order
** and pPreferredIdx is one of those indices, then return pPreferredIdx.
**
** nEqCol is the number of columns of pPreferredIdx that are used as
** equality constraints. Any index returned must have exactly this same
** set of columns. The ORDER BY clause only matches index columns beyond the
** the first nEqCol columns.
**
** All terms of the ORDER BY clause must be either ASC or DESC. The
** *pbRev value is set to 1 if the ORDER BY clause is all DESC and it is
** set to 0 if the ORDER BY clause is all ASC.
**
** TODO: If earlier terms of an ORDER BY clause match all terms of a
** UNIQUE index, then subsequent terms of the ORDER BY can be ignored.
** This optimization needs to be implemented.
*/
static Index *findSortingIndex(
Parse *pParse, /* Parsing context */
Table *pTab, /* The table to be sorted */
int base, /* Cursor number for pTab */
ExprList *pOrderBy, /* The ORDER BY clause */
Index *pPreferredIdx, /* Use this index, if possible and not NULL */
int nEqCol, /* Number of index columns used with == constraints */
int *pbRev /* Set to 1 if ORDER BY is DESC */
){
int i, j; /* Loop counters */
Index *pMatch; /* Best matching index so far */
Index *pIdx; /* Current index */
int sortOrder; /* Which direction we are sorting */
sqlite3 *db = pParse->db;
assert( pOrderBy!=0 );
assert( pOrderBy->nExpr>0 );
assert( pPreferredIdx!=0 || nEqCol==0 );
sortOrder = pOrderBy->a[0].sortOrder;
for(i=0; i<pOrderBy->nExpr; i++){
Expr *p;
if( pOrderBy->a[i].sortOrder!=sortOrder ){
/* Indices can only be used if all ORDER BY terms are either
** DESC or ASC. Indices cannot be used on a mixture. */
return 0;
}
p = pOrderBy->a[i].pExpr;
if( p->op!=TK_COLUMN || p->iTable!=base ){
/* Can not use an index sort on anything that is not a column in the
** left-most table of the FROM clause */
return 0;
}
}
/* If we get this far, it means the ORDER BY clause consists of columns
** that are all either ascending or descending and which refer only to
** the left-most table of the FROM clause. Find the index that is best
** used for sorting.
*/
pMatch = 0;
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
int nExpr = pOrderBy->nExpr;
if( pIdx->nColumn < nEqCol || pIdx->nColumn < nExpr ) continue;
for(i=j=0; i<nEqCol; i++){
CollSeq *pColl = sqlite3ExprCollSeq(pParse, pOrderBy->a[j].pExpr);
if( !pColl ) pColl = db->pDfltColl;
if( pPreferredIdx->aiColumn[i]!=pIdx->aiColumn[i] ) break;
if( pPreferredIdx->keyInfo.aColl[i]!=pIdx->keyInfo.aColl[i] ) break;
if( j<nExpr &&
pOrderBy->a[j].pExpr->iColumn==pIdx->aiColumn[i] &&
pColl==pIdx->keyInfo.aColl[i]
){
j++;
}
}
if( i<nEqCol ) continue;
for(i=0; i+j<nExpr; i++){
CollSeq *pColl = sqlite3ExprCollSeq(pParse, pOrderBy->a[i+j].pExpr);
if( !pColl ) pColl = db->pDfltColl;
if( pOrderBy->a[i+j].pExpr->iColumn!=pIdx->aiColumn[i+nEqCol] ||
pColl!=pIdx->keyInfo.aColl[i+nEqCol] ) break;
}
if( i+j>=nExpr ){
pMatch = pIdx;
if( pIdx==pPreferredIdx ) break;
}
}
*pbRev = sortOrder==SQLITE_SO_DESC;
return pMatch;
}
/*
** This routine decides if pIdx can be used to satisfy the ORDER BY
** clause. If it can, it returns 1. If pIdx cannot satisfy the
** ORDER BY clause, this routine returns 0.
**
** pOrderBy is an ORDER BY clause from a SELECT statement. pTab is the
** left-most table in the FROM clause of that same SELECT statement and
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if( pExpr->op!=TK_COLUMN || pExpr->iTable!=base ){
/* Can not use an index sort on anything that is not a column in the
** left-most table of the FROM clause */
return 0;
}
pColl = sqlite3ExprCollSeq(pParse, pExpr);
if( !pColl ) pColl = db->pDfltColl;
if( pExpr->iColumn!=pIdx->aiColumn[i] && pColl!=pIdx->keyInfo.aColl[i] ){
if( i<=nEqCol ){
if( pExpr->iColumn!=pIdx->aiColumn[i] || pColl!=pIdx->keyInfo.aColl[i] ){
/* Term j of the ORDER BY clause does not match column i of the index */
if( i<nEqCol ){
/* If an index column that is constrained by == fails to match an
** ORDER BY term, that is OK. Just ignore that column of the index
*/
continue;
}else{
/* If an index column fails to match and is not constrained by ==
** then the index cannot satisfy the ORDER BY constraint.
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assert( pX->op==TK_EQ );
sqlite3ExprCode(pParse, pX->pRight);
}else{
int iTab = pX->iTable;
Vdbe *v = pParse->pVdbe;
sqlite3VdbeAddOp(v, OP_Rewind, iTab, brk);
sqlite3VdbeAddOp(v, OP_KeyAsData, iTab, 1);
pLevel->inP2 = sqlite3VdbeAddOp(v, OP_IdxColumn, iTab, 0);
pLevel->inP2 = sqlite3VdbeAddOp(v, OP_Column, iTab, 0);
pLevel->inOp = OP_Next;
pLevel->inP1 = iTab;
}
disableTerm(pLevel, &pTerm->p);
}
/*
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){
int i; /* Loop counter */
WhereInfo *pWInfo; /* Will become the return value of this function */
Vdbe *v = pParse->pVdbe; /* The virtual database engine */
int brk, cont = 0; /* Addresses used during code generation */
int nExpr; /* Number of subexpressions in the WHERE clause */
Bitmask loopMask; /* One bit set for each outer loop */
int haveKey = 0; /* True if KEY is on the stack */
int haveRowid = 0; /* True if the ROWID is on the stack */
ExprInfo *pTerm; /* A single term in the WHERE clause; ptr to aExpr[] */
ExprMaskSet maskSet; /* The expression mask set */
int iDirectEq[BMS]; /* Term of the form ROWID==X for the N-th table */
int iDirectLt[BMS]; /* Term of the form ROWID<X or ROWID<=X */
int iDirectGt[BMS]; /* Term of the form ROWID>X or ROWID>=X */
ExprInfo aExpr[101]; /* The WHERE clause is divided into these terms */
struct SrcList_item *pTabItem; /* A single entry from pTabList */
WhereLevel *pLevel; /* A single level in the pWInfo list */
/* pushKey is only allowed if there is a single table (as in an INSERT or
** UPDATE statement)
*/
assert( pushKey==0 || pTabList->nSrc==1 );
/* Split the WHERE clause into separate subexpressions where each
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** doing a second read of the actual database table.
**
** Actually, if there are more than 32 tables in the join, only the
** first 32 tables are candidates for indices. This is (again) due
** to the limit of 32 bits in an integer bitmask.
*/
loopMask = 0;
pTabItem = pTabList->a;
pLevel = pWInfo->a;
for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(iDirectEq); i++){
for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(iDirectEq); i++,pTabItem++,pLevel++){
int j;
WhereLevel *pLevel = &pWInfo->a[i];
int iCur = pTabList->a[i].iCursor; /* The cursor for this table */
int iCur = pTabItem->iCursor; /* The cursor for this table */
Bitmask mask = getMask(&maskSet, iCur); /* Cursor mask for this table */
Table *pTab = pTabList->a[i].pTab;
Table *pTab = pTabItem->pTab;
Index *pIdx;
Index *pBestIdx = 0;
int bestScore = 0;
int bestRev = 0;
/* Check to see if there is an expression that uses only the
** ROWID field of this table. For terms of the form ROWID==expr
** set iDirectEq[i] to the index of the term. For terms of the
** form ROWID<expr or ROWID<=expr set iDirectLt[i] to the term index.
** For terms like ROWID>expr or ROWID>=expr set iDirectGt[i].
**
** (Added:) Treat ROWID IN expr like ROWID=expr.
*/
pLevel->iCur = -1;
pLevel->iIdxCur = -1;
iDirectEq[i] = -1;
iDirectLt[i] = -1;
iDirectGt[i] = -1;
for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){
Expr *pX = pTerm->p;
if( pTerm->idxLeft==iCur && pX->pLeft->iColumn<0
&& (pTerm->prereqRight & loopMask)==pTerm->prereqRight ){
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m = ((Bitmask)1)<<nEq;
if( m & ltMask ) score+=4; /* Increase score for a < constraint */
if( m & gtMask ) score+=8; /* Increase score for a > constraint */
if( score==0 && inMask ) score = 16; /* Default score for IN constraint */
/* Give bonus points if this index can be used for sorting
*/
if( i==0 && score>0 && ppOrderBy && *ppOrderBy ){
if( i==0 && score!=16 && ppOrderBy && *ppOrderBy ){
int base = pTabList->a[0].iCursor;
if( isSortingIndex(pParse, pIdx, pTab, base, *ppOrderBy, nEq, &bRev) ){
score += 2;
}
}
/* Check to see if we can get away with using just the index without
** ever reading the table. If that is the case, then add one bonus
** point to the score.
*/
if( score && pTabItem->colUsed < (((Bitmask)1)<<(BMS-1)) ){
for(m=0, j=0; j<pIdx->nColumn; j++){
int x = pIdx->aiColumn[j];
if( x<BMS-1 ){
m |= ((Bitmask)1)<<x;
}
}
if( (pTabItem->colUsed & m)==pTabItem->colUsed ){
score++;
}
}
/* If the score for this index is the best we have seen so far, then
** save it
*/
if( score>bestScore ){
pBestIdx = pIdx;
bestScore = score;
bestRev = bRev;
}
}
pLevel->pIdx = pBestIdx;
pLevel->score = bestScore;
pLevel->bRev = bestRev;
loopMask |= mask;
if( pBestIdx ){
pLevel->iCur = pParse->nTab++;
pLevel->iIdxCur = pParse->nTab++;
}
}
/* Check to see if the ORDER BY clause is or can be satisfied by the
** use of an index on the first table.
*/
if( ppOrderBy && *ppOrderBy && pTabList->nSrc>0 ){
Index *pSortIdx = 0; /* Index that satisfies the ORDER BY clause */
Index *pIdx; /* Index derived from the WHERE clause */
Table *pTab; /* Left-most table in the FROM clause */
int bRev = 0; /* True to reverse the output order */
int iCur; /* Btree-cursor that will be used by pTab */
WhereLevel *pLevel0 = &pWInfo->a[0];
pTab = pTabList->a[0].pTab;
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** So, pretend that no suitable index is found.
*/
}else if( iDirectEq[0]>=0 || iDirectLt[0]>=0 || iDirectGt[0]>=0 ){
/* If the left-most column is accessed using its ROWID, then do
** not try to sort by index. But do delete the ORDER BY clause
** if it is redundant.
*/
}else{
int nEqCol = (pLevel0->score+16)/32;
pSortIdx = findSortingIndex(pParse, pTab, iCur,
*ppOrderBy, pIdx, nEqCol, &bRev);
}else if( (pLevel0->score&2)!=0 ){
/* The index that was selected for searching will cause rows to
** appear in sorted order.
*/
}
if( pSortIdx && (pIdx==0 || pIdx==pSortIdx) ){
if( pIdx==0 ){
pLevel0->pIdx = pSortIdx;
pLevel0->iCur = pParse->nTab++;
}
pLevel0->bRev = bRev;
*ppOrderBy = 0;
}
}
/* Open all tables in the pTabList and all indices used by those tables.
/* Open all tables in the pTabList and any indices selected for
** searching those tables.
*/
sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */
pLevel = pWInfo->a;
for(i=0; i<pTabList->nSrc; i++){
for(i=0, pTabItem=pTabList->a; i<pTabList->nSrc; i++, pTabItem++, pLevel++){
Table *pTab;
Index *pIx;
int iIdxCur = pLevel->iIdxCur;
pTab = pTabList->a[i].pTab;
pTab = pTabItem->pTab;
if( pTab->isTransient || pTab->pSelect ) continue;
if( (pLevel->score & 1)==0 ){
sqlite3OpenTableForReading(v, pTabList->a[i].iCursor, pTab);
sqlite3OpenTableForReading(v, pTabItem->iCursor, pTab);
sqlite3CodeVerifySchema(pParse, pTab->iDb);
if( (pIx = pWInfo->a[i].pIdx)!=0 ){
}
pLevel->iTabCur = pTabItem->iCursor;
if( (pIx = pLevel->pIdx)!=0 ){
sqlite3VdbeAddOp(v, OP_Integer, pIx->iDb, 0);
sqlite3VdbeOp3(v, OP_OpenRead, pWInfo->a[i].iCur, pIx->tnum,
sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIx->tnum,
(char*)&pIx->keyInfo, P3_KEYINFO);
}
if( (pLevel->score & 1)!=0 ){
sqlite3VdbeAddOp(v, OP_KeyAsData, iIdxCur, 1);
sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, pIx->nColumn+1);
}
sqlite3CodeVerifySchema(pParse, pTab->iDb);
}
pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
/* Generate the code to do the search
*/
loopMask = 0;
pLevel = pWInfo->a;
pTabItem = pTabList->a;
for(i=0; i<pTabList->nSrc; i++){
for(i=0; i<pTabList->nSrc; i++, pTabItem++, pLevel++){
int j, k;
int iCur = pTabList->a[i].iCursor;
Index *pIdx;
WhereLevel *pLevel = &pWInfo->a[i];
int iCur = pTabItem->iCursor; /* The VDBE cursor for the table */
Index *pIdx; /* The index we will be using */
int iIdxCur; /* The VDBE cursor for the index */
int omitTable; /* True if we use the index only */
pIdx = pLevel->pIdx;
iIdxCur = pLevel->iIdxCur;
pLevel->inOp = OP_Noop;
/* Check to see if it is appropriate to omit the use of the table
** here and use its index instead.
*/
omitTable = (pLevel->score&1)!=0;
/* If this is the right table of a LEFT OUTER JOIN, allocate and
** initialize a memory cell that records if this table matches any
** row of the left table of the join.
*/
if( i>0 && (pTabList->a[i-1].jointype & JT_LEFT)!=0 ){
if( !pParse->nMem ) pParse->nMem++;
pLevel->iLeftJoin = pParse->nMem++;
sqlite3VdbeAddOp(v, OP_String8, 0, 0);
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
VdbeComment((v, "# init LEFT JOIN no-match flag"));
}
pIdx = pLevel->pIdx;
pLevel->inOp = OP_Noop;
if( i<ARRAYSIZE(iDirectEq) && (k = iDirectEq[i])>=0 ){
/* Case 1: We can directly reference a single row using an
** equality comparison against the ROWID field. Or
** we reference multiple rows using a "rowid IN (...)"
** construct.
*/
assert( k<nExpr );
pTerm = &aExpr[k];
assert( pTerm->p!=0 );
assert( pTerm->idxLeft==iCur );
assert( omitTable==0 );
brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
codeEqualityTerm(pParse, pTerm, brk, pLevel);
cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
sqlite3VdbeAddOp(v, OP_MustBeInt, 1, brk);
haveKey = 0;
sqlite3VdbeAddOp(v, OP_NotExists, iCur, brk);
haveRowid = 0;
pLevel->op = OP_Noop;
}else if( pIdx!=0 && pLevel->score>0 && (pLevel->score&0x0c)==0 ){
}else if( pIdx!=0 && pLevel->score>3 && (pLevel->score&0x0c)==0 ){
/* Case 2: There is an index and all terms of the WHERE clause that
** refer to the index using the "==" or "IN" operators.
*/
int start;
int nColumn = (pLevel->score+16)/32;
brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
|
︙ | | |
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1128
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|
/* Generate code (1) to move to the first matching element of the table.
** Then generate code (2) that jumps to "brk" after the cursor is past
** the last matching element of the table. The code (1) is executed
** once to initialize the search, the code (2) is executed before each
** iteration of the scan to see if the scan has finished. */
if( pLevel->bRev ){
/* Scan in reverse order */
sqlite3VdbeAddOp(v, OP_MoveLe, pLevel->iCur, brk);
sqlite3VdbeAddOp(v, OP_MoveLe, iIdxCur, brk);
start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqlite3VdbeAddOp(v, OP_IdxLT, pLevel->iCur, brk);
sqlite3VdbeAddOp(v, OP_IdxLT, iIdxCur, brk);
pLevel->op = OP_Prev;
}else{
/* Scan in the forward order */
sqlite3VdbeAddOp(v, OP_MoveGe, pLevel->iCur, brk);
sqlite3VdbeAddOp(v, OP_MoveGe, iIdxCur, brk);
start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqlite3VdbeOp3(v, OP_IdxGE, pLevel->iCur, brk, "+", P3_STATIC);
sqlite3VdbeOp3(v, OP_IdxGE, iIdxCur, brk, "+", P3_STATIC);
pLevel->op = OP_Next;
}
sqlite3VdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0);
sqlite3VdbeAddOp(v, OP_IdxIsNull, nColumn, cont);
sqlite3VdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
if( i==pTabList->nSrc-1 && pushKey ){
haveKey = 1;
if( omitTable ){
haveRowid = 0;
}else{
sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
haveKey = 0;
sqlite3VdbeAddOp(v, OP_IdxRecno, iIdxCur, 0);
haveRowid = 1;
}
pLevel->p1 = pLevel->iCur;
pLevel->p1 = iIdxCur;
pLevel->p2 = start;
}else if( i<ARRAYSIZE(iDirectLt) && (iDirectLt[i]>=0 || iDirectGt[i]>=0) ){
/* Case 3: We have an inequality comparison against the ROWID field.
*/
int testOp = OP_Noop;
int start;
int bRev = pLevel->bRev;
assert( omitTable==0 );
brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
if( bRev ){
int t = iDirectGt[i];
iDirectGt[i] = iDirectLt[i];
iDirectLt[i] = t;
}
|
︙ | | |
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pLevel->p1 = iCur;
pLevel->p2 = start;
if( testOp!=OP_Noop ){
sqlite3VdbeAddOp(v, OP_Recno, iCur, 0);
sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqlite3VdbeAddOp(v, testOp, 0, brk);
}
haveKey = 0;
haveRowid = 0;
}else if( pIdx==0 ){
/* Case 4: There is no usable index. We must do a complete
** scan of the entire database table.
*/
int start;
int opRewind;
assert( omitTable==0 );
brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
if( pLevel->bRev ){
opRewind = OP_Last;
pLevel->op = OP_Prev;
}else{
opRewind = OP_Rewind;
pLevel->op = OP_Next;
}
sqlite3VdbeAddOp(v, opRewind, iCur, brk);
start = sqlite3VdbeCurrentAddr(v);
pLevel->p1 = iCur;
pLevel->p2 = start;
haveKey = 0;
haveRowid = 0;
}else{
/* Case 5: The WHERE clause term that refers to the right-most
** column of the index is an inequality. For example, if
** the index is on (x,y,z) and the WHERE clause is of the
** form "x=5 AND y<10" then this case is used. Only the
** right-most column can be an inequality - the rest must
** use the "==" operator.
|
︙ | | |
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}
if( testOp!=OP_Noop ){
int nCol = nEqColumn + ((score & 4)!=0);
pLevel->iMem = pParse->nMem++;
buildIndexProbe(v, nCol, brk, pIdx);
if( pLevel->bRev ){
int op = leFlag ? OP_MoveLe : OP_MoveLt;
sqlite3VdbeAddOp(v, op, pLevel->iCur, brk);
sqlite3VdbeAddOp(v, op, iIdxCur, brk);
}else{
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
}
}else if( pLevel->bRev ){
sqlite3VdbeAddOp(v, OP_Last, pLevel->iCur, brk);
sqlite3VdbeAddOp(v, OP_Last, iIdxCur, brk);
}
/* Generate the start key. This is the key that defines the lower
** bound on the search. There is no start key if there are no
** equality terms and if there is no "X>..." term. In
** that case, generate a "Rewind" instruction in place of the
** start key search.
|
︙ | | |
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|
buildIndexProbe(v, nCol, brk, pIdx);
if( pLevel->bRev ){
pLevel->iMem = pParse->nMem++;
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
testOp = OP_IdxLT;
}else{
int op = geFlag ? OP_MoveGe : OP_MoveGt;
sqlite3VdbeAddOp(v, op, pLevel->iCur, brk);
sqlite3VdbeAddOp(v, op, iIdxCur, brk);
}
}else if( pLevel->bRev ){
testOp = OP_Noop;
}else{
sqlite3VdbeAddOp(v, OP_Rewind, pLevel->iCur, brk);
sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, brk);
}
/* Generate the the top of the loop. If there is a termination
** key we have to test for that key and abort at the top of the
** loop.
*/
start = sqlite3VdbeCurrentAddr(v);
if( testOp!=OP_Noop ){
sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqlite3VdbeAddOp(v, testOp, pLevel->iCur, brk);
sqlite3VdbeAddOp(v, testOp, iIdxCur, brk);
if( (leFlag && !pLevel->bRev) || (!geFlag && pLevel->bRev) ){
sqlite3VdbeChangeP3(v, -1, "+", P3_STATIC);
}
}
sqlite3VdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0);
sqlite3VdbeAddOp(v, OP_IdxIsNull, nEqColumn + ((score&4)!=0), cont);
sqlite3VdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
if( i==pTabList->nSrc-1 && pushKey ){
haveKey = 1;
if( omitTable ){
haveRowid = 0;
}else{
sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
haveKey = 0;
sqlite3VdbeAddOp(v, OP_IdxRecno, iIdxCur, 0);
haveRowid = 1;
}
/* Record the instruction used to terminate the loop.
*/
pLevel->op = pLevel->bRev ? OP_Prev : OP_Next;
pLevel->p1 = pLevel->iCur;
pLevel->p1 = iIdxCur;
pLevel->p2 = start;
}
loopMask |= getMask(&maskSet, iCur);
/* Insert code to test every subexpression that can be completely
** computed using the current set of tables.
*/
for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){
if( pTerm->p==0 ) continue;
if( (pTerm->prereqAll & loopMask)!=pTerm->prereqAll ) continue;
if( pLevel->iLeftJoin && !ExprHasProperty(pTerm->p,EP_FromJoin) ){
continue;
}
if( haveKey ){
haveKey = 0;
if( haveRowid ){
haveRowid = 0;
if( omitTable ){
sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
}else{
sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
}
}
sqlite3ExprIfFalse(pParse, pTerm->p, cont, 1);
pTerm->p = 0;
}
brk = cont;
/* For a LEFT OUTER JOIN, generate code that will record the fact that
** at least one row of the right table has matched the left table.
*/
if( pLevel->iLeftJoin ){
pLevel->top = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp(v, OP_Integer, 1, 0);
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
VdbeComment((v, "# record LEFT JOIN hit"));
for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){
if( pTerm->p==0 ) continue;
if( (pTerm->prereqAll & loopMask)!=pTerm->prereqAll ) continue;
if( haveKey ){
/* Cannot happen. "haveKey" can only be true if pushKey is true
if( haveRowid ){
/* Cannot happen. "haveRowid" can only be true if pushKey is true
** an pushKey can only be true for DELETE and UPDATE and there are
** no outer joins with DELETE and UPDATE.
*/
assert( 0 );
haveKey = 0;
haveRowid = 0;
sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
}
sqlite3ExprIfFalse(pParse, pTerm->p, cont, 1);
pTerm->p = 0;
}
}
}
if( haveRowid && (i<pTabList->nSrc-1 || !pushKey) ){
haveRowid = 0;
if( omitTable ){
sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
}else{
sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
}
}
}
pWInfo->iContinue = cont;
if( pushKey && !haveKey ){
if( pushKey && !haveRowid ){
sqlite3VdbeAddOp(v, OP_Recno, pTabList->a[0].iCursor, 0);
}
freeMaskSet(&maskSet);
return pWInfo;
}
/*
** Generate the end of the WHERE loop. See comments on
** sqlite3WhereBegin() for additional information.
*/
void sqlite3WhereEnd(WhereInfo *pWInfo){
Vdbe *v = pWInfo->pParse->pVdbe;
int i;
WhereLevel *pLevel;
SrcList *pTabList = pWInfo->pTabList;
struct SrcList_item *pTabItem;
/* Generate loop termination code.
*/
for(i=pTabList->nSrc-1; i>=0; i--){
pLevel = &pWInfo->a[i];
sqlite3VdbeResolveLabel(v, pLevel->cont);
if( pLevel->op!=OP_Noop ){
sqlite3VdbeAddOp(v, pLevel->op, pLevel->p1, pLevel->p2);
}
sqlite3VdbeResolveLabel(v, pLevel->brk);
if( pLevel->inOp!=OP_Noop ){
sqlite3VdbeAddOp(v, pLevel->inOp, pLevel->inP1, pLevel->inP2);
}
if( pLevel->iLeftJoin ){
int addr;
addr = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iLeftJoin, 0);
sqlite3VdbeAddOp(v, OP_NotNull, 1, addr+4 + (pLevel->iCur>=0));
sqlite3VdbeAddOp(v, OP_NotNull, 1, addr+4 + (pLevel->iIdxCur>=0));
sqlite3VdbeAddOp(v, OP_NullRow, pTabList->a[i].iCursor, 0);
if( pLevel->iCur>=0 ){
sqlite3VdbeAddOp(v, OP_NullRow, pLevel->iCur, 0);
if( pLevel->iIdxCur>=0 ){
sqlite3VdbeAddOp(v, OP_NullRow, pLevel->iIdxCur, 0);
}
sqlite3VdbeAddOp(v, OP_Goto, 0, pLevel->top);
}
}
/* The "break" point is here, just past the end of the outer loop.
** Set it.
*/
sqlite3VdbeResolveLabel(v, pWInfo->iBreak);
/* Close all of the cursors
*/
pLevel = pWInfo->a;
pTabItem = pTabList->a;
for(i=0; i<pTabList->nSrc; i++){
Table *pTab = pTabList->a[i].pTab;
for(i=0; i<pTabList->nSrc; i++, pTabItem++, pLevel++){
Table *pTab = pTabItem->pTab;
assert( pTab!=0 );
if( pTab->isTransient || pTab->pSelect ) continue;
pLevel = &pWInfo->a[i];
sqlite3VdbeAddOp(v, OP_Close, pTabList->a[i].iCursor, 0);
if( (pLevel->score & 1)==0 ){
sqlite3VdbeAddOp(v, OP_Close, pTabItem->iCursor, 0);
}
if( pLevel->pIdx!=0 ){
sqlite3VdbeAddOp(v, OP_Close, pLevel->iCur, 0);
sqlite3VdbeAddOp(v, OP_Close, pLevel->iIdxCur, 0);
}
}
/* Make all cursor substitutions for cases where we want to use
** just the index and never reference the table.
**
** Calls to the code generator in between sqlite3WhereBegin and
** sqlite3WhereEnd will have created code that references the table
** directly. This loop scans all that code looking for opcodes
** that reference the table and converts them into opcodes that
** reference the index.
*/
if( pLevel->score & 1 ){
int i, j, last;
VdbeOp *pOp;
Index *pIdx = pLevel->pIdx;
assert( pIdx!=0 );
pOp = sqlite3VdbeGetOp(v, pWInfo->iTop);
last = sqlite3VdbeCurrentAddr(v);
for(i=pWInfo->iTop; i<last; i++, pOp++){
if( pOp->p1!=pLevel->iTabCur ) continue;
if( pOp->opcode==OP_Column ){
pOp->p1 = pLevel->iIdxCur;
for(j=0; j<pIdx->nColumn; j++){
if( pOp->p2==pIdx->aiColumn[j] ){
pOp->p2 = j;
break;
}
}
}else if( pOp->opcode==OP_Recno ){
pOp->p1 = pLevel->iIdxCur;
pOp->opcode = OP_IdxRecno;
}
}
}
}
/* Final cleanup
*/
sqliteFree(pWInfo);
return;
}
|