From bc76695c4c44e21aed94ee2bea81c4cdcedf1390 Mon Sep 17 00:00:00 2001
From: Simon Riggs <simon@2ndQuadrant.com>
Date: Fri, 18 Feb 2011 15:07:26 +0000
Subject: [PATCH] Make a hard state change from catchup to streaming mode. More
useful state change for monitoring purposes, plus a required change for
synchronous replication patch.
---
src/backend/replication/walsender.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index e04d59e1e77..eb99246e6d2 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -369,6 +369,16 @@ StartReplication(StartReplicationCmd * cmd)
(errcode(ERRCODE_CANNOT_CONNECT_NOW),
errmsg("standby connections not allowed because wal_level=minimal")));
+ /*
+ * When we first start replication the standby will be behind the primary.
+ * For some applications, for example, synchronous replication, it is
+ * important to have a clear state for this initial catchup mode, so we
+ * can trigger actions when we change streaming state later. We may stay
+ * in this state for a long time, which is exactly why we want to be
+ * able to monitor whether or not we are still here.
+ */
+ WalSndSetState(WALSNDSTATE_CATCHUP);
+
/* Send a CopyBothResponse message, and start streaming */
pq_beginmessage(&buf, 'W');
pq_sendbyte(&buf, 0);
@@ -752,8 +762,17 @@ WalSndLoop(void)
break;
}
- /* Update our state to indicate if we're behind or not */
- WalSndSetState(caughtup ? WALSNDSTATE_STREAMING : WALSNDSTATE_CATCHUP);
+ /*
+ * If we're in catchup state, see if its time to move to streaming.
+ * This is an important state change for users, since before this
+ * point data loss might occur if the primary dies and we need to
+ * failover to the standby. The state change is also important for
+ * synchronous replication, since commits that started to wait at
+ * that point might wait for some time.
+ */
+ if (MyWalSnd->state == WALSNDSTATE_CATCHUP && caughtup)
+ WalSndSetState(WALSNDSTATE_STREAMING);
+
ProcessRepliesIfAny();
}
--
GitLab