[pgpool-general: 3562] Re: Multiple active PGPool servers and Statement cache

Tatsuo Ishii ishii at postgresql.org
Fri Mar 20 16:52:12 JST 2015

> Hey,
> This is more of a feature request. Once of our clients uses PGPool
> Active/Active, and they have an interest in using statement cache.
> My understanding is that this will not work, as an update to PGPool a will
> not invalidate PGPool b's cache object.


> Would it be possible to implement the sharing of statement cache
> invalidation via watchdog? Obviously this would be under the same proviso
> that standard streaming replication is: that a PGPool node may be slightly
> behind the other at any one time due to network lag.

One idea is storing invalidation info onto memcached. Pgpool-II's
query cache (statement cache) can already be on memcached and this is
not terribly hard to implement. Also this way, we could avoid the
concern you raise.

What do you think?

Best regards,
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php

> Cheers,
> James Sewell,
> PostgreSQL Team Lead / Solutions Architect
> ______________________________________
>  Level 2, 50 Queen St, Melbourne VIC 3000
> *P *(+61) 3 8370 8000  *W* www.lisasoft.com  *F *(+61) 3 8370 8099
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