Save a few cycles in plpgsql simple-expression initialization.

tglsfdc · tglsfdc · commit 37e0a016547a · 2010-10-28T13:29:13.000-04:00
Instead of using ExecPrepareExpr, call ExecInitExpr.  The net change here
is that we don't apply expression_planner() to the expression tree.  There
is no need to do so, because that tree is extracted from a fully planned
plancache entry, so all the needed work is already done.  This reduces
the setup costs by about a factor of 2 according to some simple tests.
Oversight noted while fooling around with the simple-expression code for
previous fix.
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
@@ -4577,10 +4577,11 @@ exec_eval_simple_expr(PLpgSQL_execstate *estate,
 	 */
 	if (expr->expr_simple_lxid != curlxid)
 	{
-		expr->expr_simple_state = ExecPrepareExpr(expr->expr_simple_expr,
-												  simple_eval_estate);
+		oldcontext = MemoryContextSwitchTo(simple_eval_estate->es_query_cxt);
+		expr->expr_simple_state = ExecInitExpr(expr->expr_simple_expr, NULL);
 		expr->expr_simple_in_use = false;
 		expr->expr_simple_lxid = curlxid;
+		MemoryContextSwitchTo(oldcontext);
 	}
 
 	/*

Original file line number	Diff line number	Diff line change
`@@ -4577,10 +4577,11 @@ exec_eval_simple_expr(PLpgSQL_execstate *estate,`
`4577`	`4577`	`*/`
`4578`	`4578`	`if (expr->expr_simple_lxid != curlxid)`
`4579`	`4579`	`{`
`4580`		`- expr->expr_simple_state = ExecPrepareExpr(expr->expr_simple_expr,`
`4581`		`- simple_eval_estate);`
	`4580`	`+ oldcontext = MemoryContextSwitchTo(simple_eval_estate->es_query_cxt);`
	`4581`	`+ expr->expr_simple_state = ExecInitExpr(expr->expr_simple_expr, NULL);`
`4582`	`4582`	`expr->expr_simple_in_use = false;`
`4583`	`4583`	`expr->expr_simple_lxid = curlxid;`
	`4584`	`+ MemoryContextSwitchTo(oldcontext);`
`4584`	`4585`	`}`
`4585`	`4586`
`4586`	`4587`	`/*`