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Replace the switching function ExecEvalExpr() with a macro that jumps

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directly to the appropriate per-node execution function, using a function
pointer stored by ExecInitExpr.  This speeds things up by eliminating one
level of function call.  The function-pointer technique also enables further
small improvements such as only making one-time tests once (and then
changing the function pointer).  Overall this seems to gain about 10%
on evaluation of simple expressions, which isn't earthshaking but seems
a worthwhile gain for a relatively small hack.  Per recent discussion
on pghackers.
This commit is contained in:
Tom Lane
2004-03-17 01:02:24 +00:00
parent 2c7e473434
commit c1352052ef
7 changed files with 419 additions and 309 deletions
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14
src/backend/executor/nodeMergejoin.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeMergejoin.c,v 1.63 2003/11/29 19:51:48 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/executor/nodeMergejoin.c,v 1.64 2004/03/17 01:02:23 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -191,6 +191,8 @@ MergeCompare(List *eqQual, List *compareQual, ExprContext *econtext)
eqclause = eqQual;
foreach(clause, compareQual)
{
ExprState *clauseexpr = (ExprState *) lfirst(clause);
ExprState *eqclauseexpr = (ExprState *) lfirst(eqclause);
Datum const_value;
bool isNull;
@ -200,10 +202,7 @@ MergeCompare(List *eqQual, List *compareQual, ExprContext *econtext)
*
* A NULL result is considered false.
*/
const_value = ExecEvalExpr((ExprState *) lfirst(clause),
econtext,
&isNull,
NULL);
const_value = ExecEvalExpr(clauseexpr, econtext, &isNull, NULL);
if (DatumGetBool(const_value) && !isNull)
{
@ -217,10 +216,7 @@ MergeCompare(List *eqQual, List *compareQual, ExprContext *econtext)
* key1 = key2 so we move on to the next pair of keys.
*-----------
*/
const_value = ExecEvalExpr((ExprState *) lfirst(eqclause),
econtext,
&isNull,
NULL);
const_value = ExecEvalExpr(eqclauseexpr, econtext, &isNull, NULL);
if (!DatumGetBool(const_value) || isNull)
break; /* return false */