Message-Id: <1168465722.17889.1168630713@webmail.messagingengine.com>
From: "Jeremy Haile" <jhaile@fastmail.fm>
To: "Jim C. Nasby" <jim@nasby.net>, pgsql-performance@postgresql.org
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	<20070110203556.GX12217@nasby.net>
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	<20070110212125.GZ12217@nasby.net>
Subject: Re: High inserts, bulk deletes - autovacuum vs scheduled
In-Reply-To: <20070110212125.GZ12217@nasby.net>
Date: Wed, 10 Jan 2007 16:48:42 -0500

> BTW, that's the default values for analyze... the defaults for vacuum
> are 2x that.

Yeah - I was actually more concerned that tables would need to be
analyzed more often than I was about vacuuming too often, so I used
analyze as the example.  Since my app is inserting constantly throughout
the day and querying for "recent" data - I want to make sure the query
planner realizes that there are lots of rows with new timestamps on
them.  In other words, if I run a query "select * from mytable where
timestamp > '9:00am'" - I want to make sure it hasn't been a day since
the table was analyzed, so the planner thinks there are zero rows
greater than 9:00am today.

> What's more important
> is to make sure critical tables (such as queue tables) are getting
> vacuumed frequently so that they stay small. 

Is the best way to do that usually to lower the scale factors?  Is it
ever a good approach to lower the scale factor to zero and just set the
thresholds to a pure number of rows? (when setting it for a specific
table)

Thanks,
Jeremy Haile