From a9cf48a4cf0c878684a2f52a3a88e29399b2065e Mon Sep 17 00:00:00 2001 From: Amit Kapila Date: Fri, 15 May 2020 08:10:00 +0530 Subject: [PATCH] Make COPY TO keep locks until the transaction end. COPY TO released the ACCESS SHARE lock immediately when it was done rather than holding on to it until the end of the transaction. This breaks the case where a REPEATABLE READ transaction could see an empty table if it repeats a COPY statement and somebody truncated the table in the meantime. Before 4dded12faad the lock was also released after COPY FROM, but the commit failed to notice the irregularity in COPY TO. This is old behavior but doesn't seem important enough to backpatch. Author: Laurenz Albe, based on suggestion by Robert Haas and Tom Lane Reviewed-by: Amit Kapila Discussion: https://postgr.es/m/7bcfc39d4176faf85ab317d0c26786953646a411.camel@cybertec.at --- src/backend/commands/copy.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c index ac07f75bc3..6d53dc463c 100644 --- a/src/backend/commands/copy.c +++ b/src/backend/commands/copy.c @@ -1081,13 +1081,8 @@ DoCopy(ParseState *pstate, const CopyStmt *stmt, EndCopyTo(cstate); } - /* - * Close the relation. If reading, we can release the AccessShareLock we - * got; if writing, we should hold the lock until end of transaction to - * ensure that updates will be committed before lock is released. - */ if (rel != NULL) - table_close(rel, (is_from ? NoLock : AccessShareLock)); + table_close(rel, NoLock); } /*