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Re: What's faster?

From: "D'Arcy J(dot)M(dot) Cain" <darcy(at)druid(dot)net>
To: "Keith Bottner" <kbottner(at)comcast(dot)net>,<pgsql-performance(at)postgresql(dot)org>
Subject: Re: What's faster?
Date: 2003-12-27 10:52:07
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Lists: pgsql-performance
On December 26, 2003 07:11 pm, Keith Bottner wrote:
> I have a database where the vast majority of information that is related to
> a customer never changes. However, there is a single field (i.e. balance)
> that changes potentially tens to hundreds of times per day per customer
> (customers ranging in the 1000s to 10000s). This information is not
> indexed. Because Postgres requires VACUUM ANALYZE more frequently on
> updated tables, should I break this single field out into its own table,
> and if so what kind of a speed up can I expect to achieve. I would be
> appreciative of any guidance offered.

We went through this recently.  One thing we found that may apply to you is 
how many fields in the client record have a foreign key constraint.  We find 
that tables with lots of FKeys are a lot more intensive on updates.  In our 
case it was another table, think of it as an order or header table with a 
balance, that has over 10 million records.  Sometimes we have 200,000 
transactions a day where we have to check the balance.  We eventually moved 
every field that could possibly be updated on a regular basis out to separate 
tables.  The improvement was dramatic.

D'Arcy J.M. Cain <darcy(at){druid|vex}.net>   |  Democracy is three wolves                |  and a sheep voting on
+1 416 425 1212     (DoD#0082)    (eNTP)   |  what's for dinner.

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