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When the [https://www.sqlite.org/queryplanner.html#partialsort|block sorting optimization]

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is used in a scalar subquery, be sure to exit the loop as soon as the first
valid output row is received.  Fix for ticket [cb3aa0641d9a4].

FossilOrigin-Name: cdbb0947f9ce18d6d7e29ffab5ea6a2ee5365fbb
This commit is contained in:
drh
2016-01-13 17:50:10 +00:00
parent 8656b24144
commit a04a8be2c2
4 changed files with 39 additions and 19 deletions
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21
src/select.c
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@@ -54,6 +54,7 @@ struct SortCtx {
int regReturn; /* Register holding block-output return address */
int labelBkOut; /* Start label for the block-output subroutine */
int addrSortIndex; /* Address of the OP_SorterOpen or OP_OpenEphemeral */
int labelDone; /* Jump here when done, ex: LIMIT reached */
u8 sortFlags; /* Zero or more SORTFLAG_* bits */
};
#define SORTFLAG_UseSorter 0x01 /* Use SorterOpen instead of OpenEphemeral */
@@ -516,6 +517,7 @@ static void pushOntoSorter(
int regRecord = ++pParse->nMem; /* Assembled sorter record */
int nOBSat = pSort->nOBSat; /* ORDER BY terms to skip */
int op; /* Opcode to add sorter record to sorter */
int iLimit; /* LIMIT counter */
assert( bSeq==0 || bSeq==1 );
assert( nData==1 || regData==regOrigData );
@@ -526,6 +528,9 @@ static void pushOntoSorter(
regBase = pParse->nMem + 1;
pParse->nMem += nBase;
}
assert( pSelect->iOffset==0 || pSelect->iLimit!=0 );
iLimit = pSelect->iOffset ? pSelect->iOffset+1 : pSelect->iLimit;
pSort->labelDone = sqlite3VdbeMakeLabel(v);
sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, regOrigData,
SQLITE_ECEL_DUP|SQLITE_ECEL_REF);
if( bSeq ){
@@ -534,7 +539,6 @@ static void pushOntoSorter(
if( nPrefixReg==0 ){
sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+bSeq, nData);
}
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat, regRecord);
if( nOBSat>0 ){
int regPrevKey; /* The first nOBSat columns of the previous row */
@@ -569,6 +573,10 @@ static void pushOntoSorter(
pSort->regReturn = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut);
sqlite3VdbeAddOp1(v, OP_ResetSorter, pSort->iECursor);
if( iLimit ){
sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, pSort->labelDone);
VdbeCoverage(v);
}
sqlite3VdbeJumpHere(v, addrFirst);
sqlite3ExprCodeMove(pParse, regBase, regPrevKey, pSort->nOBSat);
sqlite3VdbeJumpHere(v, addrJmp);
@@ -579,14 +587,8 @@ static void pushOntoSorter(
op = OP_IdxInsert;
}
sqlite3VdbeAddOp2(v, op, pSort->iECursor, regRecord);
if( pSelect->iLimit ){
if( iLimit ){
int addr;
int iLimit;
if( pSelect->iOffset ){
iLimit = pSelect->iOffset+1;
}else{
iLimit = pSelect->iLimit;
}
addr = sqlite3VdbeAddOp3(v, OP_IfNotZero, iLimit, 0, 1); VdbeCoverage(v);
sqlite3VdbeAddOp1(v, OP_Last, pSort->iECursor);
sqlite3VdbeAddOp1(v, OP_Delete, pSort->iECursor);
@@ -1190,7 +1192,7 @@ static void generateSortTail(
SelectDest *pDest /* Write the sorted results here */
){
Vdbe *v = pParse->pVdbe; /* The prepared statement */
int addrBreak = sqlite3VdbeMakeLabel(v); /* Jump here to exit loop */
int addrBreak = pSort->labelDone; /* Jump here to exit loop */
int addrContinue = sqlite3VdbeMakeLabel(v); /* Jump here for next cycle */
int addr;
int addrOnce = 0;
@@ -1209,6 +1211,7 @@ static void generateSortTail(
struct ExprList_item *aOutEx = p->pEList->a;
#endif
assert( addrBreak<0 );
if( pSort->labelBkOut ){
sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut);
sqlite3VdbeGoto(v, addrBreak);