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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.
This commit is contained in:
Simon Riggs 2011-02-18 15:07:26 +00:00
parent 06828c5feb
commit bc76695c4c
1 changed files with 21 additions and 2 deletions
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23
src/backend/replication/walsender.c
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@ -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();
}