[pgpool-general: 3227] Re: pgpool with Slony replication delay

Cal Heldenbrand cal at fbsdata.com
Fri Oct 17 22:06:46 JST 2014

Thank you Tatsuo,

What solution is there for implementing HA in such a scenario?  Threaded
requests, to threaded client connections, to a master/slave replication
system.  Would I have to use pgpool's Replication Mode and ditch the Slony


<cal at fbsdata.com>

On Thu, Oct 16, 2014 at 6:06 PM, Tatsuo Ishii <ishii at postgresql.org> wrote:

> > Hi everyone,
> >
> > I have encountered a problem with pgpool using Slony for replication to
> > slaves.  The client to pgpool in my case is an API, so requests come in
> > concurrently on independent connections.  If we have an insert directly
> > followed by a select for that record, the select is load balanced between
> > the master and slave, resulting in a 50% chance of a failure.  Since the
> > select ends up coming from a separate httpd child process, there is no
> way
> > to keep the insert and select in the same transaction.
> >
> > Am I missing something in the documentation and configs?  Can pgpool
> > intelligently recognize specific records that have been inserted to a
> > table, then direct all selects for that record to the master until Slony
> > has replicated it to the slaves?
> No. That's the limitaion of Slony (more presicely, asynchronous
> replication systems include streaming replication).
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
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