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Remove rows from the ephemeral table used by window functions once they are no longer required.

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FossilOrigin-Name: 6ad553192051eaa0c6d929baacde2de07b93c6d09de861028bbce55a2c9bfdd3
This commit is contained in:
dan
2019-03-13 15:29:14 +00:00
parent d446165f7d
commit b560a7194d
4 changed files with 57 additions and 14 deletions
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47
src/window.c
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@@ -611,6 +611,7 @@ void sqlite3WindowUpdate(
{ cume_distName, TK_GROUPS, TK_FOLLOWING, TK_UNBOUNDED },
{ ntileName, TK_ROWS, TK_CURRENT, TK_UNBOUNDED },
{ leadName, TK_ROWS, TK_UNBOUNDED, TK_UNBOUNDED },
{ lagName, TK_ROWS, TK_UNBOUNDED, TK_CURRENT },
};
int i;
for(i=0; i<ArraySize(aUp); i++){
@@ -1472,7 +1473,6 @@ static int windowInitAccum(Parse *pParse, Window *pMWin){
return regArg;
}
#if 0
/*
** Return true if the current frame should be cached in the ephemeral table,
** even if there are no xInverse() calls required.
@@ -1483,7 +1483,7 @@ static int windowCacheFrame(Window *pMWin){
FuncDef *pFunc = pWin->pFunc;
if( (pFunc->zName==nth_valueName)
|| (pFunc->zName==first_valueName)
|| (pFunc->zName==leadName) */
|| (pFunc->zName==leadName)
|| (pFunc->zName==lagName)
){
return 1;
@@ -1491,7 +1491,6 @@ static int windowCacheFrame(Window *pMWin){
}
return 0;
}
#endif
/*
** regOld and regNew are each the first register in an array of size
@@ -1532,6 +1531,7 @@ struct WindowCsrAndReg {
int csr;
int reg;
};
struct WindowCodeArg {
Parse *pParse;
Window *pMWin;
@@ -1539,12 +1539,16 @@ struct WindowCodeArg {
int regGosub;
int addrGosub;
int regArg;
int eDelete;
WindowCsrAndReg start;
WindowCsrAndReg current;
WindowCsrAndReg end;
};
/*
** Values that may be passed as the second argument to windowCodeOp().
*/
#define WINDOW_RETURN_ROW 1
#define WINDOW_AGGINVERSE 2
#define WINDOW_AGGSTEP 3
@@ -1701,6 +1705,11 @@ static int windowCodeOp(
break;
}
if( op==p->eDelete ){
sqlite3VdbeAddOp1(v, OP_Delete, csr);
sqlite3VdbeChangeP5(v, OPFLAG_SAVEPOSITION);
}
if( jumpOnEof ){
sqlite3VdbeAddOp2(v, OP_Next, csr, sqlite3VdbeCurrentAddr(v)+2);
ret = sqlite3VdbeAddOp0(v, OP_Goto);
@@ -1712,7 +1721,6 @@ static int windowCodeOp(
}
if( bPeer ){
int addr;
int nReg = (pMWin->pOrderBy ? pMWin->pOrderBy->nExpr : 0);
int regTmp = (nReg ? sqlite3GetTempRange(pParse, nReg) : 0);
windowReadPeerValues(p, csr, regTmp);
@@ -2154,6 +2162,37 @@ void sqlite3WindowCodeStep(
s.start.csr = s.current.csr+2;
s.end.csr = s.current.csr+3;
/* Figure out when rows may be deleted from the ephemeral table. There
** are four options - they may never be deleted (eDelete==0), they may
** be deleted as soon as they are no longer part of the window frame
** (eDelete==WINDOW_AGGINVERSE), they may be deleted as after the row
** has been returned to the caller (WINDOW_RETURN_ROW), or they may
** be deleted after they enter the frame (WINDOW_AGGSTEP). */
switch( pMWin->eStart ){
case TK_FOLLOWING: {
sqlite3 *db = pParse->db;
sqlite3_value *pVal = 0;
sqlite3ValueFromExpr(db, pMWin->pStart, db->enc,SQLITE_AFF_NUMERIC,&pVal);
if( pVal && sqlite3_value_int(pVal)>0 ){
s.eDelete = WINDOW_RETURN_ROW;
}
sqlite3ValueFree(pVal);
break;
}
case TK_UNBOUNDED:
if( windowCacheFrame(pMWin)==0 ){
if( pMWin->eEnd==TK_PRECEDING ){
s.eDelete = WINDOW_AGGSTEP;
}else{
s.eDelete = WINDOW_RETURN_ROW;
}
}
break;
default:
s.eDelete = WINDOW_AGGINVERSE;
break;
}
/* Allocate registers for the array of values from the sub-query, the
** samve values in record form, and the rowid used to insert said record
** into the ephemeral table. */