Use a complete new snaphot for COPYcopy-snapshot-fix

Signed-off-by: Sven Wegener <sven.wegener@stealer.net>

1 files changed, 12 insertions, 4 deletions

diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index f45b3304ae9..c3f728cddd5 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -1364,6 +1364,13 @@ BeginCopy(bool is_from,
 					(errcode(ERRCODE_UNDEFINED_COLUMN),
 					 errmsg("table \"%s\" does not have OIDs",
 							RelationGetRelationName(cstate->rel))));
+
+		/*
+		 * Use a new snapshot to ensure this query sees
+		 * results of any previously executed queries.
+		 */
+		if (!is_from)
+			PushActiveSnapshot(GetTransactionSnapshot());
 	}
 	else
 	{
@@ -1481,11 +1488,10 @@ BeginCopy(bool is_from,
 		}
 
 		/*
-		 * Use a snapshot with an updated command ID to ensure this query sees
+		 * Use a new snapshot to ensure this query sees
 		 * results of any previously executed queries.
 		 */
-		PushCopiedSnapshot(GetActiveSnapshot());
-		UpdateActiveSnapshotCommandId();
+		PushActiveSnapshot(GetTransactionSnapshot());
 
 		/* Create dest receiver for COPY OUT */
 		dest = CreateDestReceiver(DestCopyOut);
@@ -1838,9 +1844,11 @@ EndCopyTo(CopyState cstate)
 		ExecutorFinish(cstate->queryDesc);
 		ExecutorEnd(cstate->queryDesc);
 		FreeQueryDesc(cstate->queryDesc);
-		PopActiveSnapshot();
 	}
 
+	/* Discard snapshot */
+	PopActiveSnapshot();
+
 	/* Clean up storage */
 	EndCopy(cstate);
 }