Hi,
I cannot reproduce some scenario I found in my PostgreSQL logs.
I have two connections/processes:
Process 24755 is standard pg_backup connection with:
…
BEGIN;
SET TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ ONLY
…
LOCK TABLE gm.tableabc;
…
COPY FROM gm.tableabc
Process 5969 is normal connection where I have:
LOG: proces 5969 still waiting for AccessExclusiveLock on relations 562888531 of database 16429 after 1000.066 ms
DETAILT: Process holding the lock: 24755. Wait queue: 5969
Query that is waiting (from proces 5969) is:
CREATE TEMP TABLE IF NOT EXISTS tableabc
(
Id BIGINT DEFAULT gm.top()
) INHERITS (gm.tableabc);
I cannot reproduce what pg_dump is doing that causes waiting on proces 5969 (which lock is acquired and why). When pg_dump ends lock is released and proces 5969 continues.
I know that doing in two parallel connections:
BEGIN;
CREATE TEMP TABLE IF NOT EXISTS tableabc
(
Id BIGINT DEFAULT gm.top()
) INHERITS (gm.tableabc);
causes waiting state on second connection until the first finished, but pg_dump connection is read only…
Could you suggest me which part of pg_dump (which query) might cause that behaviour.
Artur Zając
