postgrespro.git / summary / log / commit / refs

commit    c058fc2a2b8ea25015b211186c88a6a3006f5937
Author:   Andres Freund <andres@anarazel.de>
Date:     Tue Nov 13 20:18:25 2018 +0000

    Rationalize expression context reset in ExecModifyTable().
    
    The current pattern of reseting expressions both in
    ExecProcessReturning() and ExecOnConflictUpdate() makes it harder than
    necessary to reason about memory lifetimes.  It also requires
    materializing slots unnecessarily, although this patch doesn't take
    advantage of the fact that that's not necessary anymore.
    
    Instead reset the expression context once for each input tuple.
    
    Author: Ashutosh Bapat
    Discussion: https://postgr.es/m/20181105210039.hh4vvi4vwoq5ba2q@alap3.anarazel.de


 src/backend/executor/nodeModifyTable.c | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index e2836b75ff..6ef694d5a4 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -163,12 +163,6 @@ ExecProcessReturning(ResultRelInfo *resultRelInfo,
 	ProjectionInfo *projectReturning = resultRelInfo->ri_projectReturning;
 	ExprContext *econtext = projectReturning->pi_exprContext;
 
-	/*
-	 * Reset per-tuple memory context to free any expression evaluation
-	 * storage allocated in the previous cycle.
-	 */
-	ResetExprContext(econtext);
-
 	/* Make tuple and any needed join variables available to ExecProject */
 	if (tupleSlot)
 		econtext->ecxt_scantuple = tupleSlot;
@@ -1453,13 +1447,7 @@ ExecOnConflictUpdate(ModifyTableState *mtstate,
 			elog(ERROR, "unrecognized heap_lock_tuple status: %u", test);
 	}
 
-	/*
-	 * Success, the tuple is locked.
-	 *
-	 * Reset per-tuple memory context to free any expression evaluation
-	 * storage allocated in the previous cycle.
-	 */
-	ResetExprContext(econtext);
+	/* Success, the tuple is locked. */
 
 	/*
 	 * Verify that the tuple is visible to our MVCC snapshot if the current
@@ -2028,6 +2016,14 @@ ExecModifyTable(PlanState *pstate)
 		 */
 		ResetPerTupleExprContext(estate);
 
+		/*
+		 * Reset per-tuple memory context used for processing on conflict and
+		 * returning clauses, to free any expression evaluation storage
+		 * allocated in the previous cycle.
+		 */
+		if (pstate->ps_ExprContext)
+			ResetExprContext(pstate->ps_ExprContext);
+
 		planSlot = ExecProcNode(subplanstate);
 
 		if (TupIsNull(planSlot))


[parent: 6a744413ea0c]