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COALESCE() and NULLIF() are now first-class expressions, not macros

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that turn into CASE expressions.  They evaluate their arguments at most
once.  Patch by Kris Jurka, review and (very light) editorializing by me.
This commit is contained in:
Tom Lane
2003-02-16 02:30:39 +00:00
parent de25638d2f
commit 51972a9d5d
22 changed files with 644 additions and 107 deletions
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15
src/backend/parser/parse_clause.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.109 2003/02/13 20:45:21 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.110 2003/02/16 02:30:38 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -922,17 +922,10 @@ buildMergedJoinVar(JoinType jointype, Var *l_colvar, Var *r_colvar)
* Here we must build a COALESCE expression to ensure that
* the join output is non-null if either input is.
*/
CaseExpr *c = makeNode(CaseExpr);
CaseWhen *w = makeNode(CaseWhen);
NullTest *n = makeNode(NullTest);
CoalesceExpr *c = makeNode(CoalesceExpr);
n->arg = (Expr *) l_node;
n->nulltesttype = IS_NOT_NULL;
w->expr = (Expr *) n;
w->result = (Expr *) l_node;
c->casetype = outcoltype;
c->args = makeList1(w);
c->defresult = (Expr *) r_node;
c->coalescetype = outcoltype;
c->args = makeList2(l_node, r_node);
res_node = (Node *) c;
break;
}