memory_context_change.patch

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index d8c5dd3..abc34aa 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -54,6 +54,7 @@
 #include "utils/rel.h"
 #include "utils/selfuncs.h"
 #include "utils/lsyscache.h"
+#include "utils/memutils.h"
 #include "utils/syscache.h"
 
 
@@ -192,6 +193,9 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	Plan	   *top_plan;
 	ListCell   *lp,
 			   *lr;
+	MemoryContext	temp_context;
+	int			i;
+	MemoryContext	default_context;
 
 	/* Cursor options may come from caller or from DECLARE CURSOR stmt */
 	if (parse->utilityStmt &&
@@ -432,6 +436,24 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	result->invalItems = glob->invalItems;
 	result->nParamExec = glob->nParamExec;
 
+	temp_context = AllocSetContextCreate(CurrentMemoryContext,
+										   "TemporaryContext",
+										   ALLOCSET_DEFAULT_SIZES);
+
+	/* Test the time impact of creating and destroying 1000 memory contexts. */
+	for (i = 0; i < 1000; i++)
+	{
+		RelOptInfo *rel;
+		default_context = MemoryContextSwitchTo(temp_context);
+		rel = makeNode(RelOptInfo);
+		pfree(rel);
+		MemoryContextSwitchTo(default_context);
+		MemoryContextResetAndDeleteChildren(temp_context);
+	}
+
+	MemoryContextSwitchTo(default_context);
+	MemoryContextDelete(temp_context);
+
 	return result;
 }