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Ensure that the result of evaluating a function during constant-expression

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simplification gets detoasted before it is incorporated into a Const node.
Otherwise, if an immutable function were to return a TOAST pointer (an
unlikely case, but it can be made to happen), we would end up with a plan
that depends on the continued existence of the out-of-line toast datum.
This commit is contained in:
Tom Lane 2007-10-11 21:28:39 +00:00
parent 245dd2bca7
commit b7f1fe6c46
1 changed files with 14 additions and 3 deletions
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17
src/backend/optimizer/util/clauses.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.109.2.1 2005/04/14 21:44:46 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.109.2.2 2007/10/11 21:28:39 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -1702,9 +1702,20 @@ simplify_op_or_func(Expr *expr, List *args)
const_val = ExecEvalExprSwitchContext((Node *) newexpr, econtext,
&const_is_null, NULL);
/* Must copy result out of sub-context used by expression eval */
/*
* Must copy result out of sub-context used by expression eval.
*
* Also, if it's varlena, forcibly detoast it. This protects us against
* storing TOAST pointers into plans that might outlive the referenced
* data.
*/
if (!const_is_null)
const_val = datumCopy(const_val, resultTypByVal, resultTypLen);
{
if (resultTypLen == -1)
const_val = PointerGetDatum(PG_DETOAST_DATUM_COPY(const_val));
else
const_val = datumCopy(const_val, resultTypByVal, resultTypLen);
}
FreeExprContext(econtext);
pfree(newexpr);