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f5905aa7be3a44909f108583ad07a54eeb60f37c
sqlite/src/where.c
drh f5905aa7be NULL values are distinct. A comparison involving a NULL is always false. 
Operations on a NULL value yield a NULL result.  This change makes SQLite
operate more like the SQL spec, but it may break existing applications that
assumed the old behavior.  All the old tests pass but we still need to add
new tests to better verify the new behavior.  Fix for ticket #44. (CVS 589)

FossilOrigin-Name: 9051173742f1b0e15a809d12a0c9c98fd2c4614d
2002-05-26 20:54:33 +00:00

860 lines
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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. Also found here are subroutines
** to generate VDBE code to evaluate expressions.
**
** $Id: where.c,v 1.48 2002/05/26 20:54:34 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.
*/
typedef struct ExprInfo ExprInfo;
struct ExprInfo {
Expr *p; /* Pointer to the subexpression */
int indexable; /* True if this subexprssion is usable by an index */
int idxLeft; /* p->pLeft is a column in this table number. -1 if
** p->pLeft is not the column of any table */
int idxRight; /* p->pRight is a column in this table number. -1 if
** p->pRight is not the column of any table */
unsigned prereqLeft; /* Tables referenced by p->pLeft */
unsigned prereqRight; /* Tables referenced by p->pRight */
unsigned prereqAll; /* Tables referenced by this expression in any way */
};
/*
** Determine the number of elements in an array.
*/
#define ARRAYSIZE(X) (sizeof(X)/sizeof(X[0]))
/*
** This routine is used to divide the WHERE expression into subexpressions
** separated by the AND operator.
**
** aSlot[] is an array of subexpressions structures.
** There are nSlot spaces left in this array. This routine attempts to
** split pExpr into subexpressions and fills aSlot[] with those subexpressions.
** The return value is the number of slots filled.
*/
static int exprSplit(int nSlot, ExprInfo *aSlot, Expr *pExpr){
int cnt = 0;
if( pExpr==0 || nSlot<1 ) return 0;
if( nSlot==1 || pExpr->op!=TK_AND ){
aSlot[0].p = pExpr;
return 1;
}
if( pExpr->pLeft->op!=TK_AND ){
aSlot[0].p = pExpr->pLeft;
cnt = 1 + exprSplit(nSlot-1, &aSlot[1], pExpr->pRight);
}else{
cnt = exprSplit(nSlot, aSlot, pExpr->pRight);
cnt += exprSplit(nSlot-cnt, &aSlot[cnt], pExpr->pLeft);
}
return cnt;
}
/*
** This routine walks (recursively) an expression tree and generates
** a bitmask indicating which tables are used in that expression
** tree. Bit 0 of the mask is set if table 0 is used. But 1 is set
** if table 1 is used. And so forth.
**
** In order for this routine to work, the calling function must have
** previously invoked sqliteExprResolveIds() on the expression. See
** the header comment on that routine for additional information.
**
** "base" is the cursor number (the value of the iTable field) that
** corresponds to the first entry in the table list.
*/
static int exprTableUsage(int base, Expr *p){
unsigned int mask = 0;
if( p==0 ) return 0;
if( p->op==TK_COLUMN ){
return 1<< (p->iTable - base);
}
if( p->pRight ){
mask = exprTableUsage(base, p->pRight);
}
if( p->pLeft ){
mask |= exprTableUsage(base, p->pLeft);
}
if( p->pList ){
int i;
for(i=0; i<p->pList->nExpr; i++){
mask |= exprTableUsage(base, p->pList->a[i].pExpr);
}
}
return mask;
}
/*
** Return TRUE if the given operator is one of the operators that is
** allowed for an indexable WHERE clause. The allowed operators are
** "=", "<", ">", "<=", and ">=".
*/
static int allowedOp(int op){
switch( op ){
case TK_LT:
case TK_LE:
case TK_GT:
case TK_GE:
case TK_EQ:
return 1;
default:
return 0;
}
}
/*
** The input to this routine is an ExprInfo structure with only the
** "p" field filled in. The job of this routine is to analyze the
** subexpression and populate all the other fields of the ExprInfo
** structure.
**
** "base" is the cursor number (the value of the iTable field) that
** corresponds to the first entry in the table list.
*/
static void exprAnalyze(int base, ExprInfo *pInfo){
Expr *pExpr = pInfo->p;
pInfo->prereqLeft = exprTableUsage(base, pExpr->pLeft);
pInfo->prereqRight = exprTableUsage(base, pExpr->pRight);
pInfo->prereqAll = exprTableUsage(base, pExpr);
pInfo->indexable = 0;
pInfo->idxLeft = -1;
pInfo->idxRight = -1;
if( allowedOp(pExpr->op) && (pInfo->prereqRight & pInfo->prereqLeft)==0 ){
if( pExpr->pRight->op==TK_COLUMN ){
pInfo->idxRight = pExpr->pRight->iTable - base;
pInfo->indexable = 1;
}
if( pExpr->pLeft->op==TK_COLUMN ){
pInfo->idxLeft = pExpr->pLeft->iTable - base;
pInfo->indexable = 1;
}
}
}
/*
** Generating 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 sqliteWhereEnd() with the return value of this function
** in order to complete the WHERE clause processing.
**
** If an error occurs, this routine returns NULL.
*/
WhereInfo *sqliteWhereBegin(
Parse *pParse, /* The parser context */
int base, /* VDBE cursor index for left-most table in pTabList */
SrcList *pTabList, /* A list of all tables to be scanned */
Expr *pWhere, /* The WHERE clause */
int pushKey /* If TRUE, leave the table key on the stack */
){
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; /* Addresses used during code generation */
int *aOrder; /* Order in which pTabList entries are searched */
int nExpr; /* Number of subexpressions in the WHERE clause */
int loopMask; /* One bit set for each outer loop */
int haveKey; /* True if KEY is on the stack */
int aDirect[32]; /* If TRUE, then index this table using ROWID */
int iDirectEq[32]; /* Term of the form ROWID==X for the N-th table */
int iDirectLt[32]; /* Term of the form ROWID<X or ROWID<=X */
int iDirectGt[32]; /* Term of the form ROWID>X or ROWID>=X */
ExprInfo aExpr[50]; /* The WHERE clause is divided into these expressions */
/* Allocate space for aOrder[] and aiMem[]. */
aOrder = sqliteMalloc( sizeof(int) * pTabList->nSrc );
/* Allocate and initialize the WhereInfo structure that will become the
** return value.
*/
pWInfo = sqliteMalloc( sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel));
if( sqlite_malloc_failed ){
sqliteFree(aOrder);
sqliteFree(pWInfo);
return 0;
}
pWInfo->pParse = pParse;
pWInfo->pTabList = pTabList;
pWInfo->base = base;
pWInfo->peakNTab = pWInfo->savedNTab = pParse->nTab;
pWInfo->iBreak = sqliteVdbeMakeLabel(v);
/* Special case: a WHERE clause that is constant. Evaluate the
** expression and either jump over all of the code or fall thru.
*/
if( pWhere && sqliteExprIsConstant(pWhere) ){
sqliteExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1);
}
/* Split the WHERE clause into as many as 32 separate subexpressions
** where each subexpression is separated by an AND operator. Any additional
** subexpressions are attached in the aExpr[32] and will not enter
** into the query optimizer computations. 32 is chosen as the cutoff
** since that is the number of bits in an integer that we use for an
** expression-used mask.
*/
memset(aExpr, 0, sizeof(aExpr));
nExpr = exprSplit(ARRAYSIZE(aExpr), aExpr, pWhere);
/* Analyze all of the subexpressions.
*/
for(i=0; i<nExpr; i++){
exprAnalyze(base, &aExpr[i]);
/* If we are executing a trigger body, remove all references to
** new.* and old.* tables from the prerequisite masks.
*/
if( pParse->trigStack ){
int x;
if( (x = pParse->trigStack->newIdx) >= 0 ){
int mask = ~(1 << (x - base));
aExpr[i].prereqRight &= mask;
aExpr[i].prereqLeft &= mask;
aExpr[i].prereqAll &= mask;
}
if( (x = pParse->trigStack->oldIdx) >= 0 ){
int mask = ~(1 << (x - base));
aExpr[i].prereqRight &= mask;
aExpr[i].prereqLeft &= mask;
aExpr[i].prereqAll &= mask;
}
}
}
/* Figure out a good nesting order for the tables. aOrder[0] will
** be the index in pTabList of the outermost table. aOrder[1] will
** be the first nested loop and so on. aOrder[pTabList->nSrc-1] will
** be the innermost loop.
**
** Someday we will put in a good algorithm here to reorder the loops
** for an effiecient query. But for now, just use whatever order the
** tables appear in in the pTabList.
*/
for(i=0; i<pTabList->nSrc; i++){
aOrder[i] = i;
}
/* Figure out what index to use (if any) for each nested loop.
** Make pWInfo->a[i].pIdx point to the index to use for the i-th nested
** loop where i==0 is the outer loop and i==pTabList->nSrc-1 is the inner
** loop.
**
** If terms exist that use the ROWID of any table, then set the
** iDirectEq[], iDirectLt[], or iDirectGt[] elements for that table
** to the index of the term containing the ROWID. We always prefer
** to use a ROWID which can directly access a table rather than an
** index which requires reading an index first to get the rowid then
** 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;
for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(aDirect); i++){
int j;
int idx = aOrder[i];
Table *pTab = pTabList->a[idx].pTab;
Index *pIdx;
Index *pBestIdx = 0;
int bestScore = 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].
*/
iDirectEq[i] = -1;
iDirectLt[i] = -1;
iDirectGt[i] = -1;
for(j=0; j<nExpr; j++){
if( aExpr[j].idxLeft==idx && aExpr[j].p->pLeft->iColumn<0
&& (aExpr[j].prereqRight & loopMask)==aExpr[j].prereqRight ){
switch( aExpr[j].p->op ){
case TK_EQ: iDirectEq[i] = j; break;
case TK_LE:
case TK_LT: iDirectLt[i] = j; break;
case TK_GE:
case TK_GT: iDirectGt[i] = j; break;
}
}
if( aExpr[j].idxRight==idx && aExpr[j].p->pRight->iColumn<0
&& (aExpr[j].prereqLeft & loopMask)==aExpr[j].prereqLeft ){
switch( aExpr[j].p->op ){
case TK_EQ: iDirectEq[i] = j; break;
case TK_LE:
case TK_LT: iDirectGt[i] = j; break;
case TK_GE:
case TK_GT: iDirectLt[i] = j; break;
}
}
}
if( iDirectEq[i]>=0 ){
loopMask |= 1<<idx;
pWInfo->a[i].pIdx = 0;
continue;
}
/* Do a search for usable indices. Leave pBestIdx pointing to
** the "best" index. pBestIdx is left set to NULL if no indices
** are usable.
**
** The best index is determined as follows. For each of the
** left-most terms that is fixed by an equality operator, add
** 4 to the score. The right-most term of the index may be
** constrained by an inequality. Add 1 if for an "x<..." constraint
** and add 2 for an "x>..." constraint. Chose the index that
** gives the best score.
**
** This scoring system is designed so that the score can later be
** used to determine how the index is used. If the score&3 is 0
** then all constraints are equalities. If score&1 is not 0 then
** there is an inequality used as a termination key. (ex: "x<...")
** If score&2 is not 0 then there is an inequality used as the
** start key. (ex: "x>...");
*/
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
int eqMask = 0; /* Index columns covered by an x=... constraint */
int ltMask = 0; /* Index columns covered by an x<... constraint */
int gtMask = 0; /* Index columns covered by an x>... constraing */
int nEq, m, score;
if( pIdx->isDropped ) continue; /* Ignore dropped indices */
if( pIdx->nColumn>32 ) continue; /* Ignore indices too many columns */
for(j=0; j<nExpr; j++){
if( aExpr[j].idxLeft==idx
&& (aExpr[j].prereqRight & loopMask)==aExpr[j].prereqRight ){
int iColumn = aExpr[j].p->pLeft->iColumn;
int k;
for(k=0; k<pIdx->nColumn; k++){
if( pIdx->aiColumn[k]==iColumn ){
switch( aExpr[j].p->op ){
case TK_EQ: {
eqMask |= 1<<k;
break;
}
case TK_LE:
case TK_LT: {
ltMask |= 1<<k;
break;
}
case TK_GE:
case TK_GT: {
gtMask |= 1<<k;
break;
}
default: {
/* CANT_HAPPEN */
assert( 0 );
break;
}
}
break;
}
}
}
if( aExpr[j].idxRight==idx
&& (aExpr[j].prereqLeft & loopMask)==aExpr[j].prereqLeft ){
int iColumn = aExpr[j].p->pRight->iColumn;
int k;
for(k=0; k<pIdx->nColumn; k++){
if( pIdx->aiColumn[k]==iColumn ){
switch( aExpr[j].p->op ){
case TK_EQ: {
eqMask |= 1<<k;
break;
}
case TK_LE:
case TK_LT: {
gtMask |= 1<<k;
break;
}
case TK_GE:
case TK_GT: {
ltMask |= 1<<k;
break;
}
default: {
/* CANT_HAPPEN */
assert( 0 );
break;
}
}
break;
}
}
}
}
for(nEq=0; nEq<pIdx->nColumn; nEq++){
m = (1<<(nEq+1))-1;
if( (m & eqMask)!=m ) break;
}
score = nEq*4;
m = 1<<nEq;
if( m & ltMask ) score++;
if( m & gtMask ) score+=2;
if( score>bestScore ){
pBestIdx = pIdx;
bestScore = score;
}
}
pWInfo->a[i].pIdx = pBestIdx;
pWInfo->a[i].score = bestScore;
loopMask |= 1<<idx;
if( pBestIdx ){
pWInfo->a[i].iCur = pParse->nTab++;
pWInfo->peakNTab = pParse->nTab;
}
}
/* Open all tables in the pTabList and all indices used by those tables.
*/
for(i=0; i<pTabList->nSrc; i++){
int openOp;
Table *pTab;
pTab = pTabList->a[i].pTab;
if( pTab->isTransient || pTab->pSelect ) continue;
openOp = pTab->isTemp ? OP_OpenAux : OP_Open;
sqliteVdbeAddOp(v, openOp, base+i, pTab->tnum);
sqliteVdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
if( i==0 && !pParse->schemaVerified &&
(pParse->db->flags & SQLITE_InTrans)==0 ){
sqliteVdbeAddOp(v, OP_VerifyCookie, pParse->db->schema_cookie, 0);
pParse->schemaVerified = 1;
}
if( pWInfo->a[i].pIdx!=0 ){
sqliteVdbeAddOp(v, openOp, pWInfo->a[i].iCur, pWInfo->a[i].pIdx->tnum);
sqliteVdbeChangeP3(v, -1, pWInfo->a[i].pIdx->zName, P3_STATIC);
}
}
/* Generate the code to do the search
*/
loopMask = 0;
for(i=0; i<pTabList->nSrc; i++){
int j, k;
int idx = aOrder[i];
Index *pIdx;
WhereLevel *pLevel = &pWInfo->a[i];
/* If this is the right table of a LEFT OUTER JOIN, allocate and
** initialize a memory cell that record if this table matches any
** row of the left table in the join.
*/
if( i>0 && (pTabList->a[i-1].jointype & JT_LEFT)!=0 ){
if( !pParse->nMem ) pParse->nMem++;
pLevel->iLeftJoin = pParse->nMem++;
sqliteVdbeAddOp(v, OP_String, 0, 0);
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
}
pIdx = pLevel->pIdx;
if( i<ARRAYSIZE(iDirectEq) && iDirectEq[i]>=0 ){
/* Case 1: We can directly reference a single row using an
** equality comparison against the ROWID field.
*/
k = iDirectEq[i];
assert( k<nExpr );
assert( aExpr[k].p!=0 );
assert( aExpr[k].idxLeft==idx || aExpr[k].idxRight==idx );
if( aExpr[k].idxLeft==idx ){
sqliteExprCode(pParse, aExpr[k].p->pRight);
}else{
sqliteExprCode(pParse, aExpr[k].p->pLeft);
}
aExpr[k].p = 0;
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
cont = pLevel->cont = brk;
sqliteVdbeAddOp(v, OP_MustBeInt, 0, brk);
if( i==pTabList->nSrc-1 && pushKey ){
/* Note: The OP_Dup below will cause the recno to be left on the
** stack if the record does not exists and the OP_NotExists jump is
** taken. This violates a general rule of the VDBE that you should
** never leave values on the stack in order to avoid a stack overflow.
** But in this case, the OP_Dup will never happen inside of a loop,
** because the pushKey flag is only true for UPDATE and DELETE, not
** for SELECT, and nested loops only occur on a SELECT.
** So it is safe to leave the recno on the stack.
*/
haveKey = 1;
sqliteVdbeAddOp(v, OP_Dup, 0, 0);
}else{
haveKey = 0;
}
sqliteVdbeAddOp(v, OP_NotExists, base+idx, brk);
pLevel->op = OP_Noop;
}else if( pIdx!=0 && pLevel->score%4==0 ){
/* Case 2: All index constraints are equality operators.
*/
int start;
int testOp;
int nColumn = pLevel->score/4;
for(j=0; j<nColumn; j++){
for(k=0; k<nExpr; k++){
if( aExpr[k].p==0 ) continue;
if( aExpr[k].idxLeft==idx
&& aExpr[k].p->op==TK_EQ
&& (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
&& aExpr[k].p->pLeft->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, aExpr[k].p->pRight);
aExpr[k].p = 0;
break;
}
if( aExpr[k].idxRight==idx
&& aExpr[k].p->op==TK_EQ
&& (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
&& aExpr[k].p->pRight->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, aExpr[k].p->pLeft);
aExpr[k].p = 0;
break;
}
}
}
pLevel->iMem = pParse->nMem++;
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
cont = pLevel->cont = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_MakeKey, nColumn, 0);
if( nColumn==pIdx->nColumn ){
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 0);
testOp = OP_IdxGT;
}else{
sqliteVdbeAddOp(v, OP_Dup, 0, 0);
sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
testOp = OP_IdxGE;
}
sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk);
start = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqliteVdbeAddOp(v, testOp, pLevel->iCur, brk);
sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
if( i==pTabList->nSrc-1 && pushKey ){
haveKey = 1;
}else{
sqliteVdbeAddOp(v, OP_MoveTo, base+idx, 0);
haveKey = 0;
}
pLevel->op = OP_Next;
pLevel->p1 = pLevel->iCur;
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;
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
cont = pLevel->cont = sqliteVdbeMakeLabel(v);
if( iDirectGt[i]>=0 ){
k = iDirectGt[i];
assert( k<nExpr );
assert( aExpr[k].p!=0 );
assert( aExpr[k].idxLeft==idx || aExpr[k].idxRight==idx );
if( aExpr[k].idxLeft==idx ){
sqliteExprCode(pParse, aExpr[k].p->pRight);
}else{
sqliteExprCode(pParse, aExpr[k].p->pLeft);
}
sqliteVdbeAddOp(v, OP_MustBeInt, 0, brk);
if( aExpr[k].p->op==TK_LT || aExpr[k].p->op==TK_GT ){
sqliteVdbeAddOp(v, OP_AddImm, 1, 0);
}
sqliteVdbeAddOp(v, OP_MoveTo, base+idx, brk);
aExpr[k].p = 0;
}else{
sqliteVdbeAddOp(v, OP_Rewind, base+idx, brk);
}
if( iDirectLt[i]>=0 ){
k = iDirectLt[i];
assert( k<nExpr );
assert( aExpr[k].p!=0 );
assert( aExpr[k].idxLeft==idx || aExpr[k].idxRight==idx );
if( aExpr[k].idxLeft==idx ){
sqliteExprCode(pParse, aExpr[k].p->pRight);
}else{
sqliteExprCode(pParse, aExpr[k].p->pLeft);
}
sqliteVdbeAddOp(v, OP_MustBeInt, 0, sqliteVdbeCurrentAddr(v)+1);
pLevel->iMem = pParse->nMem++;
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 0);
if( aExpr[k].p->op==TK_LT || aExpr[k].p->op==TK_GT ){
testOp = OP_Ge;
}else{
testOp = OP_Gt;
}
aExpr[k].p = 0;
}
start = sqliteVdbeCurrentAddr(v);
pLevel->op = OP_Next;
pLevel->p1 = base+idx;
pLevel->p2 = start;
if( testOp!=OP_Noop ){
sqliteVdbeAddOp(v, OP_Recno, base+idx, 0);
sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqliteVdbeAddOp(v, testOp, 0, brk);
}
haveKey = 0;
}else if( pIdx==0 ){
/* Case 4: There was no usable index. We must do a complete
** scan of the entire database table.
*/
int start;
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
cont = pLevel->cont = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_Rewind, base+idx, brk);
start = sqliteVdbeCurrentAddr(v);
pLevel->op = OP_Next;
pLevel->p1 = base+idx;
pLevel->p2 = start;
haveKey = 0;
}else{
/* Case 5: The contraint on the right-most index field is
** an inequality.
*/
int score = pLevel->score;
int nEqColumn = score/4;
int start;
int leFlag, geFlag;
int testOp;
/* Evaluate the equality constraints
*/
for(j=0; j<nEqColumn; j++){
for(k=0; k<nExpr; k++){
if( aExpr[k].p==0 ) continue;
if( aExpr[k].idxLeft==idx
&& aExpr[k].p->op==TK_EQ
&& (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
&& aExpr[k].p->pLeft->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, aExpr[k].p->pRight);
aExpr[k].p = 0;
break;
}
if( aExpr[k].idxRight==idx
&& aExpr[k].p->op==TK_EQ
&& (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
&& aExpr[k].p->pRight->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, aExpr[k].p->pLeft);
aExpr[k].p = 0;
break;
}
}
}
/* Duplicate the equality contraint values because they will all be
** used twice: once to make the termination key and once to make the
** start key.
*/
for(j=0; j<nEqColumn; j++){
sqliteVdbeAddOp(v, OP_Dup, nEqColumn-1, 0);
}
/* Generate the termination key. This is the key value that
** will end the search. There is no termination key if there
** are no equality contraints and no "X<..." constraint.
*/
if( (score & 1)!=0 ){
for(k=0; k<nExpr; k++){
Expr *pExpr = aExpr[k].p;
if( pExpr==0 ) continue;
if( aExpr[k].idxLeft==idx
&& (pExpr->op==TK_LT || pExpr->op==TK_LE)
&& (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
&& pExpr->pLeft->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, pExpr->pRight);
leFlag = pExpr->op==TK_LE;
aExpr[k].p = 0;
break;
}
if( aExpr[k].idxRight==idx
&& (pExpr->op==TK_GT || pExpr->op==TK_GE)
&& (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
&& pExpr->pRight->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, pExpr->pLeft);
leFlag = pExpr->op==TK_GE;
aExpr[k].p = 0;
break;
}
}
testOp = OP_IdxGE;
}else{
testOp = nEqColumn>0 ? OP_IdxGE : OP_Noop;
leFlag = 1;
}
if( testOp!=OP_Noop ){
pLevel->iMem = pParse->nMem++;
sqliteVdbeAddOp(v, OP_MakeKey, nEqColumn + (score & 1), 0);
if( leFlag ){
sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
}
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
}
/* Generate the start key. This is the key that defines the lower
** bound on the search. There is no start key if there are not
** equality constraints and if there is no "X>..." constraint. In
** that case, generate a "Rewind" instruction in place of the
** start key search.
*/
if( (score & 2)!=0 ){
for(k=0; k<nExpr; k++){
Expr *pExpr = aExpr[k].p;
if( pExpr==0 ) continue;
if( aExpr[k].idxLeft==idx
&& (pExpr->op==TK_GT || pExpr->op==TK_GE)
&& (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
&& pExpr->pLeft->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, pExpr->pRight);
geFlag = pExpr->op==TK_GE;
aExpr[k].p = 0;
break;
}
if( aExpr[k].idxRight==idx
&& (pExpr->op==TK_LT || pExpr->op==TK_LE)
&& (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
&& pExpr->pRight->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, pExpr->pLeft);
geFlag = pExpr->op==TK_LE;
aExpr[k].p = 0;
break;
}
}
}else{
geFlag = 1;
}
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
cont = pLevel->cont = sqliteVdbeMakeLabel(v);
if( nEqColumn>0 || (score&2)!=0 ){
sqliteVdbeAddOp(v, OP_MakeKey, nEqColumn + ((score&2)!=0), 0);
if( !geFlag ){
sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
}
sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk);
}else{
sqliteVdbeAddOp(v, OP_Rewind, pLevel->iCur, 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 = sqliteVdbeCurrentAddr(v);
if( testOp!=OP_Noop ){
sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqliteVdbeAddOp(v, testOp, pLevel->iCur, brk);
}
sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
if( i==pTabList->nSrc-1 && pushKey ){
haveKey = 1;
}else{
sqliteVdbeAddOp(v, OP_MoveTo, base+idx, 0);
haveKey = 0;
}
/* Record the instruction used to terminate the loop.
*/
pLevel->op = OP_Next;
pLevel->p1 = pLevel->iCur;
pLevel->p2 = start;
}
loopMask |= 1<<idx;
/* Insert code to test every subexpression that can be completely
** computed using the current set of tables.
*/
for(j=0; j<nExpr; j++){
if( aExpr[j].p==0 ) continue;
if( (aExpr[j].prereqAll & loopMask)!=aExpr[j].prereqAll ) continue;
if( haveKey ){
haveKey = 0;
sqliteVdbeAddOp(v, OP_MoveTo, base+idx, 0);
}
sqliteExprIfFalse(pParse, aExpr[j].p, cont, 1);
aExpr[j].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 = sqliteVdbeCurrentAddr(v);
sqliteVdbeAddOp(v, OP_Integer, 1, 0);
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
}
}
pWInfo->iContinue = cont;
if( pushKey && !haveKey ){
sqliteVdbeAddOp(v, OP_Recno, base, 0);
}
sqliteFree(aOrder);
return pWInfo;
}
/*
** Generate the end of the WHERE loop.
*/
void sqliteWhereEnd(WhereInfo *pWInfo){
Vdbe *v = pWInfo->pParse->pVdbe;
int i;
int base = pWInfo->base;
WhereLevel *pLevel;
SrcList *pTabList = pWInfo->pTabList;
for(i=pTabList->nSrc-1; i>=0; i--){
pLevel = &pWInfo->a[i];
sqliteVdbeResolveLabel(v, pLevel->cont);
if( pLevel->op!=OP_Noop ){
sqliteVdbeAddOp(v, pLevel->op, pLevel->p1, pLevel->p2);
}
sqliteVdbeResolveLabel(v, pLevel->brk);
if( pLevel->iLeftJoin ){
int addr;
addr = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iLeftJoin, 0);
sqliteVdbeAddOp(v, OP_NotNull, 0, addr+4);
sqliteVdbeAddOp(v, OP_NullRow, base+i, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, pLevel->top);
}
}
sqliteVdbeResolveLabel(v, pWInfo->iBreak);
for(i=0; i<pTabList->nSrc; i++){
if( pTabList->a[i].pTab->isTransient ) continue;
pLevel = &pWInfo->a[i];
sqliteVdbeAddOp(v, OP_Close, base+i, 0);
if( pLevel->pIdx!=0 ){
sqliteVdbeAddOp(v, OP_Close, pLevel->iCur, 0);
}
}
if( pWInfo->pParse->nTab==pWInfo->peakNTab ){
pWInfo->pParse->nTab = pWInfo->savedNTab;
}
sqliteFree(pWInfo);
return;
}
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