From: Tomas Vondra <tomas.vondra@postgresql.org>
Date: Tue, 22 Jan 2019 22:11:17 +0000 (+0100)
Subject: Fix handling of volatile expressions in COPY FROM ... WHERE
X-Git-Tag: REL_12_BETA1~888
X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=4a8283d0ec5a6781b9e0d4ba16b44da8a0856d02;p=postgresql.git

Fix handling of volatile expressions in COPY FROM ... WHERE

The checking for calls to volatile functions in the COPY FROM ... WHERE
expression was treating all WHERE clauses as if containing such calls.
While that does not produce incorrect results, this disables batching
which may result in significant performance regression.

Discussion: https://www.postgresql.org/message-id/flat/CALAY4q_DdpWDuB5-Zyi-oTtO2uSk8pmy+dupiRe3AvAc++1imA@mail.gmail.com
---

diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index c410e0a0dd6..03745cca753 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -2612,8 +2612,7 @@ CopyFrom(CopyState cstate)
 		 */
 		insertMethod = CIM_SINGLE;
 	}
-	else if (cstate->whereClause != NULL ||
-			 contain_volatile_functions(cstate->whereClause))
+	else if (contain_volatile_functions(cstate->whereClause))
 	{
 		/*
 		 * Can't support multi-inserts if there are any volatile funcation