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Re: How to configure a read-only database server?

From: Greg Smith <greg(at)2ndQuadrant(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: How to configure a read-only database server?
Date: 2011-04-19 14:30:48
Message-ID: 4DAD9C98.5090707@2ndQuadrant.com (view raw or flat)
Thread:
Lists: pgsql-performance
On 04/18/2011 06:08 PM, Stefan Keller wrote:
> * What about wal_level and archive_mode?
>    

Presumably you don't care about either of these.  wal_level=minimal, 
archive_mode=off.

The other non-obvious thing you should do in this situation is do all 
the database maintenance in one big run after the data is loaded, 
something like:

VACUUM FREEZE ANALYZE;

Otherwise you will still have some trickle of write-activity going on, 
not always efficiently, despite being in read-only mode.  It's because 
of what's referred to as Hint Bits:  
http://wiki.postgresql.org/wiki/Hint_Bits

VACUUMing everything will clean those us, and freezing everything makes 
sure there's no old transactions to concerned about that might kick off 
anti-wraparound autovacuum.

The only other thing you probably want to do is set checkpoint_segments 
to a big number.  Shouldn't matter normally, but when doing this freeze 
operation it will help that execute quickly.  You want a lower 
maintenance_work_mem on a read-only system than the master too, possibly 
a higher shared_buffers as well.  It's all pretty subtle beyond the big 
parameters you already identified.

-- 
Greg Smith   2ndQuadrant US    greg(at)2ndQuadrant(dot)com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support  www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books


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