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Add window functions lag() and lead().

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FossilOrigin-Name: ef34207073c21ce8618486777671ae78d23f290acd6d3c37e91a49b69cb506ac
This commit is contained in:
dan
2018-06-07 20:08:59 +00:00
parent 7095c002b8
commit fe4e25a0f6
7 changed files with 980 additions and 14 deletions
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71
src/window.c
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@@ -325,6 +325,36 @@ static void first_valueInverseFunc(
static void first_valueValueFunc(sqlite3_context *pCtx){
}
static void leadStepFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
}
static void leadInverseFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
}
static void leadValueFunc(sqlite3_context *pCtx){
}
static void lagStepFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
}
static void lagInverseFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
}
static void lagValueFunc(sqlite3_context *pCtx){
}
#define WINDOWFUNC(name,nArg,extra) { \
nArg, (SQLITE_UTF8|SQLITE_FUNC_WINDOW|extra), 0, 0, \
name ## StepFunc, name ## ValueFunc, name ## ValueFunc, \
@@ -351,6 +381,8 @@ void sqlite3WindowFunctions(void){
WINDOWFUNCF(last_value, 1, 0),
WINDOWFUNC(nth_value, 2, 0),
WINDOWFUNC(first_value, 1, 0),
WINDOWFUNC(lead, 1, 0), WINDOWFUNC(lead, 2, 0), WINDOWFUNC(lead, 3, 0),
WINDOWFUNC(lag, 1, 0), WINDOWFUNC(lag, 2, 0), WINDOWFUNC(lag, 3, 0),
};
sqlite3InsertBuiltinFuncs(aWindowFuncs, ArraySize(aWindowFuncs));
}
@@ -659,6 +691,11 @@ static void windowAggInit(Parse *pParse, Window *pMWin){
pParse->nMem += 2;
sqlite3VdbeAddOp2(v, OP_OpenDup, pWin->csrApp, pMWin->iEphCsr);
}
else if( p->xSFunc==leadStepFunc || p->xSFunc==lagStepFunc ){
assert( pMWin->iEphCsr );
pWin->csrApp = pParse->nTab++;
sqlite3VdbeAddOp2(v, OP_OpenDup, pWin->csrApp, pMWin->iEphCsr);
}
}
}
@@ -747,6 +784,10 @@ static void windowAggStep(
);
assert( bInverse==0 || bInverse==1 );
sqlite3VdbeAddOp2(v, OP_AddImm, pWin->regApp+1-bInverse, 1);
}else if( pWin->pFunc->xSFunc==leadStepFunc
|| pWin->pFunc->xSFunc==lagStepFunc
){
/* no-op */
}else{
if( pWin->pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL ){
CollSeq *pColl;
@@ -877,6 +918,34 @@ static void windowReturnOneRow(
sqlite3VdbeResolveLabel(v, lbl);
sqlite3ReleaseTempReg(pParse, tmpReg);
}
else if( pFunc->xSFunc==leadStepFunc || pFunc->xSFunc==lagStepFunc ){
int iEph = pWin->iEphCsr;
int csr = pWin->csrApp;
int lbl = sqlite3VdbeMakeLabel(v);
int tmpReg = sqlite3GetTempReg(pParse);
if( pWin->nArg<3 ){
sqlite3VdbeAddOp2(v, OP_Null, 0, pWin->regResult);
}else{
sqlite3VdbeAddOp3(v, OP_Column, iEph, pWin->iArgCol+2, pWin->regResult);
}
sqlite3VdbeAddOp2(v, OP_Rowid, iEph, tmpReg);
if( pWin->nArg<2 ){
int val = (pFunc->xSFunc==leadStepFunc ? 1 : -1);
sqlite3VdbeAddOp2(v, OP_AddImm, tmpReg, val);
}else{
int op = (pFunc->xSFunc==leadStepFunc ? OP_Add : OP_Subtract);
int tmpReg2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_Column, iEph, pWin->iArgCol+1, tmpReg2);
sqlite3VdbeAddOp3(v, op, tmpReg2, tmpReg, tmpReg);
sqlite3ReleaseTempReg(pParse, tmpReg2);
}
sqlite3VdbeAddOp3(v, OP_SeekRowid, csr, lbl, tmpReg);
sqlite3VdbeAddOp3(v, OP_Column, csr, pWin->iArgCol, pWin->regResult);
sqlite3VdbeResolveLabel(v, lbl);
sqlite3ReleaseTempReg(pParse, tmpReg);
}
}
sqlite3VdbeAddOp2(v, OP_Gosub, regGosub, addrGosub);
}
@@ -1600,6 +1669,8 @@ void sqlite3WindowCodeStep(
if( (pFunc->funcFlags & SQLITE_FUNC_WINDOW_SIZE)
|| (pFunc->xSFunc==nth_valueStepFunc)
|| (pFunc->xSFunc==first_valueStepFunc)
|| (pFunc->xSFunc==leadStepFunc)
|| (pFunc->xSFunc==lagStepFunc)
){
windowCodeCacheStep(pParse, p, pWInfo, regGosub, addrGosub);
return;