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Avoid allocating excessive registers for the PARTITION BY expressions when processing window functions.

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FossilOrigin-Name: 180be266238e18c01f8bd52c75dd9aa3e26e553620258141cd95189a0ae59ddb
This commit is contained in:
dan
2019-03-13 17:20:27 +00:00
parent b560a7194d
commit b6f2deac3c
4 changed files with 18 additions and 20 deletions
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19
src/window.c
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@@ -1118,12 +1118,14 @@ int sqlite3WindowCompare(Parse *pParse, Window *p1, Window *p2){
void sqlite3WindowCodeInit(Parse *pParse, Window *pMWin){
Window *pWin;
Vdbe *v = sqlite3GetVdbe(pParse);
int nPart = (pMWin->pPartition ? pMWin->pPartition->nExpr : 0);
nPart += (pMWin->pOrderBy ? pMWin->pOrderBy->nExpr : 0);
if( nPart ){
/* Allocate registers to use for PARTITION BY values, if any. Initialize
** said registers to NULL. */
if( pMWin->pPartition ){
int nExpr = pMWin->pPartition->nExpr;
pMWin->regPart = pParse->nMem+1;
pParse->nMem += nPart;
sqlite3VdbeAddOp3(v, OP_Null, 0, pMWin->regPart, pMWin->regPart+nPart-1);
pParse->nMem += nExpr;
sqlite3VdbeAddOp3(v, OP_Null, 0, pMWin->regPart, pMWin->regPart+nExpr-1);
}
pMWin->regFirst = ++pParse->nMem;
@@ -2111,6 +2113,8 @@ Window *sqlite3WindowListDup(sqlite3 *db, Window *p){
** RETURN_ROW
** }
**
** The text above leaves out many details. Refer to the code and comments
** below for a more complete picture.
*/
void sqlite3WindowCodeStep(
Parse *pParse, /* Parse context */
@@ -2302,8 +2306,6 @@ void sqlite3WindowCodeStep(
sqlite3VdbeAddOp2(v, OP_Integer, 0, pMWin->regFirst);
sqlite3VdbeAddOp2(v, OP_Goto, 0, lblWhereEnd);
/* Begin generating SECOND_ROW_CODE */
VdbeModuleComment((pParse->pVdbe, "Begin WindowCodeStep.SECOND_ROW"));
sqlite3VdbeJumpHere(v, addrIfNot);
if( regPeer ){
windowIfNewPeer(pParse, pOrderBy, regNewPeer, regPeer, lblWhereEnd);
@@ -2354,7 +2356,6 @@ void sqlite3WindowCodeStep(
}
}
}
VdbeModuleComment((pParse->pVdbe, "End WindowCodeStep.SECOND_ROW"));
/* End of the main input loop */
sqlite3VdbeResolveLabel(v, lblWhereEnd);
@@ -2366,7 +2367,6 @@ void sqlite3WindowCodeStep(
sqlite3VdbeJumpHere(v, addrGosubFlush);
}
VdbeModuleComment((pParse->pVdbe, "Begin WindowCodeStep.FLUSH"));
addrEmpty = sqlite3VdbeAddOp1(v, OP_Rewind, csrWrite);
if( pMWin->eEnd==TK_PRECEDING ){
windowCodeOp(&s, WINDOW_AGGSTEP, regEnd, 0);
@@ -2413,7 +2413,6 @@ void sqlite3WindowCodeStep(
sqlite3VdbeAddOp1(v, OP_ResetSorter, s.current.csr);
sqlite3VdbeAddOp2(v, OP_Integer, 1, pMWin->regFirst);
VdbeModuleComment((pParse->pVdbe, "End WindowCodeStep.FLUSH"));
if( pMWin->pPartition ){
sqlite3VdbeChangeP1(v, addrInteger, sqlite3VdbeCurrentAddr(v));
sqlite3VdbeAddOp1(v, OP_Return, regFlushPart);