pgpool2.git / summary / log / commit / refs

commit    fb3089ba95d4703a45779130b11ffec9031f8767
Author:   Tatsuo Ishii <ishii@sraoss.co.jp>
Date:     Sun Feb 05 07:13:15 2023 +0000

    Fix sr worker to not send wrong query to standby server in corner case.
    
    When ALWAYS_PRIMARY flag is set, PRIMARY_NODE_ID macro returns node
    id, rather than -1 even if the primary is down. This confuses the test
    if a node is primary or not, because PRIMARY_NODE_ID macro returns
    main node id.  In this case streaming replication delay check worker
    sends "SELECT pg_current_wal_lsn()" or "SELECT
    pg_current_xlog_location()" depending on PostgreSQL's version to
    standby which of course raises an error.
    
    To fix this, test the primary node is down or not, and if it's down,
    skip the replication delay loop. If primary is down, there's no point
    to perform streaming replication delay checking anyway.
    
    Discussion: https://www.pgpool.net/pipermail/pgpool-hackers/2023-February/004279.html
    Backpatch-through: 4.0


 src/streaming_replication/pool_worker_child.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/streaming_replication/pool_worker_child.c b/src/streaming_replication/pool_worker_child.c
index 746f1817b..92411ea9a 100644
--- a/src/streaming_replication/pool_worker_child.c
+++ b/src/streaming_replication/pool_worker_child.c
@@ -350,6 +350,20 @@ check_replication_time_lag(void)
 		return;
 	}
 
+	if (!VALID_BACKEND(REAL_PRIMARY_NODE_ID))
+	{
+		/*
+		 * No need to check replication delay if primary is down. This could
+		 * happen if ALWAYS_PRIMARY flag is on because REAL_PRIMARY_NODE_ID
+		 * macro returns the node id which ALWAYS_PRIMARY flag is set to.  If
+		 * we do not check this, subsequent test (i == PRIMARY_NODE_ID) in the
+		 * for loop below will return unexpected result because
+		 * PRIMARY_NODE_ID macro returns MAIN_NODE_ID, which could be a
+		 * standby server.
+		 */
+		return;
+	}
+
 	/*
 	 * Register a error context callback to throw proper context message
 	 */


[parent: 66acf94322cf]