Re: Strange query stalls on replica in 9.3.9

Josh Berkus <josh@agliodbs.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