Re: How to avoid base backup in automated failover

From: Amit Kapila <amit(dot)kapila(at)huawei(dot)com>
To: "'chinnaobi'" <chinnaobi(at)gmail(dot)com>, <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: How to avoid base backup in automated failover
Date: 2012-10-17 06:51:04
Message-ID: 005401cdac33$c76ab0a0$564011e0$@kapila@huawei.com
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On Wednesday, October 17, 2012 11:22 AM chinnaobi wrote:
> Hey Haas,
>
> What does the standby server have to wait for replication to catch up
> before
> promoting ?? Is there any parameter to configure this ??
>
> Few more questions on this part
>
> 1. How could we ensure the standby has received all transactions sent by
> primary till the point primary server is dead. (Meaning the dead primary
> and
> standby server are exactly same, so that the dead primary comes back it
> can
> be turned to standby without any issues).

> 2. When the dead primary is turned to standby the streaming is not
> happening
> due to current_wal_location is ahead in the standby server is ahead of
> wal_sent_location. In this case how can I start streaming without taking
> a
> fresh base backup ??
>
> 3. When the dead primary comes back the DB still accepts data and it
> goes to
> out of sync with the current primary and streaming won't start. Is there
> any
> solution for this case ??

I think points 2 & 3 can be addressed with new feature getting implemented
by Heikki provided standby has received all WAL of primary till the point it
goes dead.

https://commitfest.postgresql.org/action/patch_view?id=933

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