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Reimplement CASE val WHEN compval1 THEN ... WHEN compval2 THEN ... END

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so that the 'val' is computed only once, per recent discussion.  The
speedup is not much when 'val' is just a simple variable, but could be
significant for larger expressions.  More importantly this avoids issues
with multiple evaluations of a volatile 'val', and it allows the CASE
expression to be reverse-listed in its original form by ruleutils.c.
This commit is contained in:
Tom Lane
2004-03-17 20:48:43 +00:00
parent 8c702ea7ac
commit 55f7c3300d
16 changed files with 248 additions and 55 deletions
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14
src/backend/nodes/outfuncs.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.232 2004/01/31 05:09:40 neilc Exp $
* $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.233 2004/03/17 20:48:42 tgl Exp $
*
* NOTES
* Every node type that can appear in stored rules' parsetrees *must*
@ -805,6 +805,15 @@ _outCaseWhen(StringInfo str, CaseWhen *node)
WRITE_NODE_FIELD(result);
}
static void
_outCaseTestExpr(StringInfo str, CaseTestExpr *node)
{
WRITE_NODE_TYPE("CASETESTEXPR");
WRITE_OID_FIELD(typeId);
WRITE_INT_FIELD(typeMod);
}
static void
_outArrayExpr(StringInfo str, ArrayExpr *node)
{
@ -1701,6 +1710,9 @@ _outNode(StringInfo str, void *obj)
case T_CaseWhen:
_outCaseWhen(str, obj);
break;
case T_CaseTestExpr:
_outCaseTestExpr(str, obj);
break;
case T_ArrayExpr:
_outArrayExpr(str, obj);
break;