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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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19
src/include/executor/executor.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/executor/executor.h,v 1.107 2004/03/02 18:56:15 tgl Exp $
* $PostgreSQL: pgsql/src/include/executor/executor.h,v 1.108 2004/03/17 01:02:24 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -17,17 +17,26 @@
#include "executor/execdesc.h"
/* ----------------
* TupIsNull
/*
* TupIsNull
*
* This is used mainly to detect when there are no more
* tuples to process.
* ----------------
*/
/* return: true if tuple in slot is NULL, slot is slot to test */
#define TupIsNull(slot) \
((slot) == NULL || (slot)->val == NULL)
/*
* ExecEvalExpr was formerly a function containing a switch statement;
* now it's just a macro invoking the function pointed to by an ExprState
* node. Beware of double evaluation of the ExprState argument!
*/
#define ExecEvalExpr(expr, econtext, isNull, isDone) \
((*(expr)->evalfunc) (expr, econtext, isNull, isDone))
/*
* prototypes from functions in execAmi.c
*/
@ -125,8 +134,6 @@ extern Tuplestorestate *ExecMakeTableFunctionResult(ExprState *funcexpr,
ExprContext *econtext,
TupleDesc expectedDesc,
TupleDesc *returnDesc);
extern Datum ExecEvalExpr(ExprState *expression, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
extern Datum ExecEvalExprSwitchContext(ExprState *expression, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
extern ExprState *ExecInitExpr(Expr *node, PlanState *parent);