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Automatically transfer terms from the HAVING clause to the WHERE clause of an

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aggregate query in cases where the result of evaluating the term depends only
one one or more of the GROUP BY expressions (and on no other inputs).

FossilOrigin-Name: 5375a3ce56f1d993b13b469fe33ec7679948f53940f62a15ddbaeb8aaa26a22c
This commit is contained in:
dan
2017-04-29 20:53:09 +00:00
parent bc43995f99
commit ab31a8450b
6 changed files with 243 additions and 20 deletions
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45
src/expr.c
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@@ -1815,6 +1815,51 @@ int sqlite3ExprIsTableConstant(Expr *p, int iCur){
return exprIsConst(p, 3, iCur);
}
/*
** sqlite3WalkExpr() callback used by sqlite3ExprIsConstantOrGroupBy().
*/
static int exprNodeIsConstantOrGroupBy(Walker *pWalker, Expr *pExpr){
ExprList *pGroupBy = pWalker->u.pGroupBy;
int i;
/* Check if pExpr is identical to any GROUP BY term. If so, consider
** it constant. */
for(i=0; i<pGroupBy->nExpr; i++){
Expr *p = pGroupBy->a[i].pExpr;
if( sqlite3ExprCompare(pExpr, p, -1)<2 ){
CollSeq *pColl = sqlite3ExprCollSeq(pWalker->pParse, p);
if( pColl==0 || sqlite3_stricmp("BINARY", pColl->zName)==0 ){
return WRC_Prune;
}
}
}
/* Check if pExpr is a sub-select. If so, consider it variable. */
if( ExprHasProperty(pExpr, EP_xIsSelect) ){
pWalker->eCode = 0;
return WRC_Abort;
}
return exprNodeIsConstant(pWalker, pExpr);
}
/*
** Walk the expression tree passed as the first argument. Return non-zero
** if the expression consists entirely of constants or copies of terms
** in pGroupBy that sort with the BINARY collation sequence.
*/
int sqlite3ExprIsConstantOrGroupBy(Parse *pParse, Expr *p, ExprList *pGroupBy){
Walker w;
memset(&w, 0, sizeof(w));
w.eCode = 1;
w.xExprCallback = exprNodeIsConstantOrGroupBy;
w.u.pGroupBy = pGroupBy;
w.pParse = pParse;
sqlite3WalkExpr(&w, p);
return w.eCode;
}
/*
** Walk an expression tree. Return non-zero if the expression is constant
** or a function call with constant arguments. Return and 0 if there