Omit all use of Expr nodes for TK_AS, as those nodes no longer served a useful
purpose and in fact interferred with the query planner.
FossilOrigin-Name: 7ab0b258eabfcfb7f1b0bd1b12e166d2f267823d
diff --git a/src/resolve.c b/src/resolve.c
index 22df223..2c4212b 100644
--- a/src/resolve.c
+++ b/src/resolve.c
@@ -45,30 +45,6 @@
** Turn the pExpr expression into an alias for the iCol-th column of the
** result set in pEList.
**
-** If the result set column is a simple column reference, then this routine
-** makes an exact copy. But for any other kind of expression, this
-** routine make a copy of the result set column as the argument to the
-** TK_AS operator. The TK_AS operator causes the expression to be
-** evaluated just once and then reused for each alias.
-**
-** The reason for suppressing the TK_AS term when the expression is a simple
-** column reference is so that the column reference will be recognized as
-** usable by indices within the WHERE clause processing logic.
-**
-** The TK_AS operator is inhibited if zType[0]=='G'. This means
-** that in a GROUP BY clause, the expression is evaluated twice. Hence:
-**
-** SELECT random()%5 AS x, count(*) FROM tab GROUP BY x
-**
-** Is equivalent to:
-**
-** SELECT random()%5 AS x, count(*) FROM tab GROUP BY random()%5
-**
-** The result of random()%5 in the GROUP BY clause is probably different
-** from the result in the result-set. On the other hand Standard SQL does
-** not allow the GROUP BY clause to contain references to result-set columns.
-** So this should never come up in well-formed queries.
-**
** If the reference is followed by a COLLATE operator, then make sure
** the COLLATE operator is preserved. For example:
**
@@ -102,19 +78,11 @@
db = pParse->db;
pDup = sqlite3ExprDup(db, pOrig, 0);
if( pDup==0 ) return;
- if( pOrig->op!=TK_COLUMN && zType[0]!='G' ){
- incrAggFunctionDepth(pDup, nSubquery);
- pDup = sqlite3PExpr(pParse, TK_AS, pDup, 0, 0);
- if( pDup==0 ) return;
- ExprSetProperty(pDup, EP_Skip);
- if( pEList->a[iCol].u.x.iAlias==0 ){
- pEList->a[iCol].u.x.iAlias = (u16)(++pParse->nAlias);
- }
- pDup->iTable = pEList->a[iCol].u.x.iAlias;
- }
+ if( zType[0]!='G' ) incrAggFunctionDepth(pDup, nSubquery);
if( pExpr->op==TK_COLLATE ){
pDup = sqlite3ExprAddCollateString(pParse, pDup, pExpr->u.zToken);
}
+ ExprSetProperty(pDup, EP_Alias);
/* Before calling sqlite3ExprDelete(), set the EP_Static flag. This
** prevents ExprDelete() from deleting the Expr structure itself,
@@ -506,7 +474,7 @@
lookupname_end:
if( cnt==1 ){
assert( pNC!=0 );
- if( pExpr->op!=TK_AS ){
+ if( !ExprHasProperty(pExpr, EP_Alias) ){
sqlite3AuthRead(pParse, pExpr, pSchema, pNC->pSrcList);
}
/* Increment the nRef value on all name contexts from TopNC up to