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Overview
| Comment: | Remove rows from the ephemeral table used by window functions once they are no longer required. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | window-functions |
| Files: | files | file ages | folders |
| SHA3-256: | 6ad553192051eaa0c6d929baacde2de0 |
| User & Date: | dan 2019-03-13 15:29:14 |
| Wiki: | window-functions |
Context
|
2019-03-13
| ||
| 17:20 | Avoid allocating excessive registers for the PARTITION BY expressions when processing window functions. check-in: 180be266 user: dan tags: window-functions | |
| 15:29 | Remove rows from the ephemeral table used by window functions once they are no longer required. check-in: 6ad55319 user: dan tags: window-functions | |
| 08:28 | Minor optimization in sqlite3WindowCodeStep(). check-in: b1322ffb user: dan tags: window-functions | |
Changes
Changes to src/btree.c.
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assert( cursorOwnsBtShared(pCur) ); assert( pBt->inTransaction==TRANS_WRITE ); assert( (pBt->btsFlags & BTS_READ_ONLY)==0 ); assert( pCur->curFlags & BTCF_WriteFlag ); assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) ); assert( !hasReadConflicts(p, pCur->pgnoRoot) ); assert( pCur->ix<pCur->pPage->nCell ); assert( pCur->eState==CURSOR_VALID ); assert( (flags & ~(BTREE_SAVEPOSITION | BTREE_AUXDELETE))==0 ); iCellDepth = pCur->iPage; iCellIdx = pCur->ix; pPage = pCur->pPage; pCell = findCell(pPage, iCellIdx); if( pPage->nFree<0 && btreeComputeFreeSpace(pPage) ) return SQLITE_CORRUPT; |
| > > > > < > |
8824 8825 8826 8827 8828 8829 8830 8831 8832 8833 8834 8835 8836 8837 8838 8839 8840 8841 8842 8843 8844 |
assert( cursorOwnsBtShared(pCur) ); assert( pBt->inTransaction==TRANS_WRITE ); assert( (pBt->btsFlags & BTS_READ_ONLY)==0 ); assert( pCur->curFlags & BTCF_WriteFlag ); assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) ); assert( !hasReadConflicts(p, pCur->pgnoRoot) ); assert( (flags & ~(BTREE_SAVEPOSITION | BTREE_AUXDELETE))==0 ); if( pCur->eState==CURSOR_REQUIRESEEK ){ rc = btreeRestoreCursorPosition(pCur); if( rc ) return rc; } assert( pCur->eState==CURSOR_VALID ); assert( pCur->ix<pCur->pPage->nCell ); iCellDepth = pCur->iPage; iCellIdx = pCur->ix; pPage = pCur->pPage; pCell = findCell(pPage, iCellIdx); if( pPage->nFree<0 && btreeComputeFreeSpace(pPage) ) return SQLITE_CORRUPT; |
Changes to src/window.c.
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{ row_numberName, TK_ROWS, TK_UNBOUNDED, TK_CURRENT },
{ dense_rankName, TK_RANGE, TK_UNBOUNDED, TK_CURRENT },
{ rankName, TK_RANGE, TK_UNBOUNDED, TK_CURRENT },
{ percent_rankName, TK_GROUPS, TK_CURRENT, TK_UNBOUNDED },
{ cume_distName, TK_GROUPS, TK_FOLLOWING, TK_UNBOUNDED },
{ ntileName, TK_ROWS, TK_CURRENT, TK_UNBOUNDED },
{ leadName, TK_ROWS, TK_UNBOUNDED, TK_UNBOUNDED },
};
int i;
for(i=0; i<ArraySize(aUp); i++){
if( pFunc->zName==aUp[i].zFunc ){
sqlite3ExprDelete(db, pWin->pStart);
sqlite3ExprDelete(db, pWin->pEnd);
pWin->pEnd = pWin->pStart = 0;
................................................................................
}
}
regArg = pParse->nMem+1;
pParse->nMem += nArg;
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.
*/
static int windowCacheFrame(Window *pMWin){
Window *pWin;
for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
FuncDef *pFunc = pWin->pFunc;
if( (pFunc->zName==nth_valueName)
|| (pFunc->zName==first_valueName)
|| (pFunc->zName==leadName) */
|| (pFunc->zName==lagName)
){
return 1;
}
}
return 0;
}
#endif
/*
** regOld and regNew are each the first register in an array of size
** pOrderBy->nExpr. This function generates code to compare the two
** arrays of registers using the collation sequences and other comparison
** parameters specified by pOrderBy.
**
................................................................................
typedef struct WindowCodeArg WindowCodeArg;
typedef struct WindowCsrAndReg WindowCsrAndReg;
struct WindowCsrAndReg {
int csr;
int reg;
};
struct WindowCodeArg {
Parse *pParse;
Window *pMWin;
Vdbe *pVdbe;
int regGosub;
int addrGosub;
int regArg;
WindowCsrAndReg start;
WindowCsrAndReg current;
WindowCsrAndReg end;
};
#define WINDOW_RETURN_ROW 1
#define WINDOW_AGGINVERSE 2
#define WINDOW_AGGSTEP 3
/*
** Generate VM code to read the window frames peer values from cursor csr into
** an array of registers starting at reg.
................................................................................
case WINDOW_AGGSTEP:
csr = p->end.csr;
reg = p->end.reg;
windowAggStep(pParse, pMWin, csr, 0, p->regArg, 0);
break;
}
if( jumpOnEof ){
sqlite3VdbeAddOp2(v, OP_Next, csr, sqlite3VdbeCurrentAddr(v)+2);
ret = sqlite3VdbeAddOp0(v, OP_Goto);
}else{
sqlite3VdbeAddOp2(v, OP_Next, csr, sqlite3VdbeCurrentAddr(v)+1+bPeer);
if( bPeer ){
addrGoto = sqlite3VdbeAddOp0(v, OP_Goto);
}
}
if( bPeer ){
int addr;
int nReg = (pMWin->pOrderBy ? pMWin->pOrderBy->nExpr : 0);
int regTmp = (nReg ? sqlite3GetTempRange(pParse, nReg) : 0);
windowReadPeerValues(p, csr, regTmp);
windowIfNewPeer(pParse, pMWin->pOrderBy, regTmp, reg, addrContinue);
sqlite3ReleaseTempRange(pParse, regTmp, nReg);
}
................................................................................
s.pVdbe = v;
s.regGosub = regGosub;
s.addrGosub = addrGosub;
s.current.csr = pMWin->iEphCsr;
csrWrite = s.current.csr+1;
s.start.csr = s.current.csr+2;
s.end.csr = s.current.csr+3;
/* 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. */
regNew = pParse->nMem+1;
pParse->nMem += nInput;
regRecord = ++pParse->nMem;
|
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{ row_numberName, TK_ROWS, TK_UNBOUNDED, TK_CURRENT },
{ dense_rankName, TK_RANGE, TK_UNBOUNDED, TK_CURRENT },
{ rankName, TK_RANGE, TK_UNBOUNDED, TK_CURRENT },
{ percent_rankName, TK_GROUPS, TK_CURRENT, TK_UNBOUNDED },
{ 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++){
if( pFunc->zName==aUp[i].zFunc ){
sqlite3ExprDelete(db, pWin->pStart);
sqlite3ExprDelete(db, pWin->pEnd);
pWin->pEnd = pWin->pStart = 0;
................................................................................
}
}
regArg = pParse->nMem+1;
pParse->nMem += nArg;
return regArg;
}
/*
** Return true if the current frame should be cached in the ephemeral table,
** even if there are no xInverse() calls required.
*/
static int windowCacheFrame(Window *pMWin){
Window *pWin;
for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
FuncDef *pFunc = pWin->pFunc;
if( (pFunc->zName==nth_valueName)
|| (pFunc->zName==first_valueName)
|| (pFunc->zName==leadName)
|| (pFunc->zName==lagName)
){
return 1;
}
}
return 0;
}
/*
** regOld and regNew are each the first register in an array of size
** pOrderBy->nExpr. This function generates code to compare the two
** arrays of registers using the collation sequences and other comparison
** parameters specified by pOrderBy.
**
................................................................................
typedef struct WindowCodeArg WindowCodeArg;
typedef struct WindowCsrAndReg WindowCsrAndReg;
struct WindowCsrAndReg {
int csr;
int reg;
};
struct WindowCodeArg {
Parse *pParse;
Window *pMWin;
Vdbe *pVdbe;
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
/*
** Generate VM code to read the window frames peer values from cursor csr into
** an array of registers starting at reg.
................................................................................
case WINDOW_AGGSTEP:
csr = p->end.csr;
reg = p->end.reg;
windowAggStep(pParse, pMWin, csr, 0, p->regArg, 0);
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);
}else{
sqlite3VdbeAddOp2(v, OP_Next, csr, sqlite3VdbeCurrentAddr(v)+1+bPeer);
if( bPeer ){
addrGoto = sqlite3VdbeAddOp0(v, OP_Goto);
}
}
if( bPeer ){
int nReg = (pMWin->pOrderBy ? pMWin->pOrderBy->nExpr : 0);
int regTmp = (nReg ? sqlite3GetTempRange(pParse, nReg) : 0);
windowReadPeerValues(p, csr, regTmp);
windowIfNewPeer(pParse, pMWin->pOrderBy, regTmp, reg, addrContinue);
sqlite3ReleaseTempRange(pParse, regTmp, nReg);
}
................................................................................
s.pVdbe = v;
s.regGosub = regGosub;
s.addrGosub = addrGosub;
s.current.csr = pMWin->iEphCsr;
csrWrite = s.current.csr+1;
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. */
regNew = pParse->nMem+1;
pParse->nMem += nInput;
regRecord = ++pParse->nMem;
|