/*
** 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 1.52 2002/06/14 22:38:43 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 "IN".
*/
static int allowedOp(int op){
switch( op ){
case TK_LT:
case TK_LE:
case TK_GT:
case TK_GE:
case TK_EQ:
case TK_IN:
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 && 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.
**
** 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 sqliteWhereBegin()
** foreach row3 in t3 do /
** ...
** end \ Code generated
** end |-- by sqliteWhereEnd()
** end /
**
** There are Btree cursors associated with each table. t1 uses cursor
** "base". t2 uses cursor "base+1". And so forth. This routine generates
** the code to open those cursors. sqliteWhereEnd() generates the code
** to close them.
**
** 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 goto start
** end
**
** In words, if the right
*/
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 */
/* pushKey is only allowed if there is a single table (as in an INSERT or
** UPDATE statement)
*/
assert( pushKey==0 || pTabList->nSrc==1 );
/* 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);
pWhere = 0;
}
/* 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_IN:
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>...");
**
** The IN operator (as in "<expr> IN (...)") is treated the same as
** an equality comparison except that it can only be used on the
** left-most column of an index and other terms of the WHERE clause
** cannot be used in conjunction with the IN operator to help satisfy
** other columns of the index.
*/
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
int eqMask = 0; /* Index columns covered by an x=... term */
int ltMask = 0; /* Index columns covered by an x<... term */
int gtMask = 0; /* Index columns covered by an x>... term */
int inMask = 0; /* Index columns covered by an x IN .. term */
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_IN: {
if( k==0 ) inMask |= 1;
break;
}
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==0 && inMask ) score = 4;
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 of 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;
pLevel->inOp = OP_Noop;
if( i<ARRAYSIZE(iDirectEq) && 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.
*/
k = iDirectEq[i];
assert( k<nExpr );
assert( aExpr[k].p!=0 );
assert( aExpr[k].idxLeft==idx || aExpr[k].idxRight==idx );
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
if( aExpr[k].idxLeft==idx ){
Expr *pX = aExpr[k].p;
if( pX->op!=TK_IN ){
sqliteExprCode(pParse, aExpr[k].p->pRight);
}else if( pX->pList ){
sqliteVdbeAddOp(v, OP_SetFirst, pX->iTable, brk);
pLevel->inOp = OP_SetNext;
pLevel->inP1 = pX->iTable;
pLevel->inP2 = sqliteVdbeCurrentAddr(v);
}else{
assert( pX->pSelect );
sqliteVdbeAddOp(v, OP_Rewind, pX->iTable, brk);
sqliteVdbeAddOp(v, OP_KeyAsData, pX->iTable, 1);
pLevel->inP2 = sqliteVdbeAddOp(v, OP_FullKey, pX->iTable, 0);
pLevel->inOp = OP_Next;
pLevel->inP1 = pX->iTable;
}
}else{
sqliteExprCode(pParse, aExpr[k].p->pLeft);
}
aExpr[k].p = 0;
cont = pLevel->cont = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_MustBeInt, 0, brk);
haveKey = 0;
sqliteVdbeAddOp(v, OP_NotExists, base+idx, brk);
pLevel->op = OP_Noop;
}else if( pIdx!=0 && pLevel->score%4==0 ){
/* Case 2: There is an index and all terms of the WHERE clause that
** refer to the index use the "==" or "IN" operators.
*/
int start;
int testOp;
int nColumn = pLevel->score/4;
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
for(j=0; j<nColumn; j++){
for(k=0; k<nExpr; k++){
Expr *pX = aExpr[k].p;
if( pX==0 ) continue;
if( aExpr[k].idxLeft==idx
&& (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
&& pX->pLeft->iColumn==pIdx->aiColumn[j]
){
if( pX->op==TK_EQ ){
sqliteExprCode(pParse, pX->pRight);
aExpr[k].p = 0;
break;
}
if( pX->op==TK_IN && nColumn==1 ){
if( pX->pList ){
sqliteVdbeAddOp(v, OP_SetFirst, pX->iTable, brk);
pLevel->inOp = OP_SetNext;
pLevel->inP1 = pX->iTable;
pLevel->inP2 = sqliteVdbeCurrentAddr(v);
}else{
assert( pX->pSelect );
sqliteVdbeAddOp(v, OP_Rewind, pX->iTable, brk);
sqliteVdbeAddOp(v, OP_KeyAsData, pX->iTable, 1);
pLevel->inP2 = sqliteVdbeAddOp(v, OP_FullKey, pX->iTable, 0);
pLevel->inOp = OP_Next;
pLevel->inP1 = pX->iTable;
}
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++;
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 is 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 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.
*/
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 term 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 terms and no "X<..." term.
*/
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 no
** equality terms and if there is no "X>..." term. 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. See comments on
** sqliteWhereBegin() for additional information.
*/
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->inOp!=OP_Noop ){
sqliteVdbeAddOp(v, pLevel->inOp, pLevel->inP1, pLevel->inP2);
}
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;
}