From: Phil Frost <phil@postmates.com>
To: pgsql-admin@postgresql.org
Subject: Replica lag, high read IO, vacuum index scanning bug?
Date: Wed, 2 Nov 2016 15:31:44 -0400
Message-ID: <3fe69397-9feb-707a-032f-968a8d48ad0f@postmates.com> (raw)
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-admin>
We are seeing an issue on RDS 9.4.5 where replica lag gets really high.
This lag seems to be correlated to a saturation of disk read throughput,
and vacuums of one of our larger and more frequently updated tables.
I've heard that there's a bug where the replica will scan indexes
unnecessarily when doing the WAL replay when the vacuums happen. Can
anyone confirm this and maybe point me towards the commit where it was
fixed? Has there been a backport to the 9.4 series?
Any other ideas for investigation or mitigation?
--
Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-admin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-admin@postgresql.org
Cc: phil@postmates.com
Subject: Re: Replica lag, high read IO, vacuum index scanning bug?
In-Reply-To: <3fe69397-9feb-707a-032f-968a8d48ad0f@postmates.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox