From: | Kevin Grittner <kgrittn(at)ymail(dot)com> |
---|---|
To: | Josh Berkus <josh(at)agliodbs(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Strange query stalls on replica in 9.3.9 |
Date: | 2015-08-13 20:24:28 |
Message-ID: | 512125623.2442595.1439497468170.JavaMail.yahoo@mail.yahoo.com |
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Lists: | pgsql-performance |
Josh Berkus <josh(at)agliodbs(dot)com> wrote:
> Periodically the master runs an "update all rows" query on the main
> table in the database. When this update hits the replica via
> replication stream, *some* (about 5%) of the queries which do seq scans
> will stall for 22 to 32 seconds (these queries normally take about
> 75ms). Queries which do index scans seem not to be affected.
>
> Thing is, the update all rows only takes 2.5 seconds to execute on the
> master. So even if the update is blocking the seq scans on the replica
> (and I can't see why it would), it should only block them for < 3 seconds.
Visibility hinting and/or hot pruning?
--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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