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Make constant-folding produce sane output for COALESCE(NULL,NULL),

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that is a plain NULL and not a COALESCE with no inputs.  Fixes crash
reported by Michael Williamson.
This commit is contained in:
Tom Lane 2005-04-10 20:58:03 +00:00
parent 5c5c797cb2
commit 29028762a9
1 changed files with 5 additions and 1 deletions
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6
src/backend/optimizer/util/clauses.c
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@ -8,7 +8,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.154.2.2 2004/01/28 00:05:25 tgl Exp $ * $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.154.2.3 2005/04/10 20:58:03 tgl Exp $
* *
* HISTORY * HISTORY
* AUTHOR DATE MAJOR EVENT * AUTHOR DATE MAJOR EVENT
@ -1553,6 +1553,10 @@ eval_const_expressions_mutator(Node *node, List *active_fns)
FastAppend(&newargs, e); FastAppend(&newargs, e);
} }
/* If all the arguments were constant null, the result is just null */
if (FastListValue(&newargs) == NIL)
return (Node *) makeNullConst(coalesceexpr->coalescetype);
newcoalesce = makeNode(CoalesceExpr); newcoalesce = makeNode(CoalesceExpr);
newcoalesce->coalescetype = coalesceexpr->coalescetype; newcoalesce->coalescetype = coalesceexpr->coalescetype;
newcoalesce->args = FastListValue(&newargs); newcoalesce->args = FastListValue(&newargs);