From: | "Bort, Paul" <pbort(at)tmwsystems(dot)com> |
---|---|
To: | "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: delete/recreate indexes |
Date: | 2011-10-20 13:24:45 |
Message-ID: | A56C12C60A05604A9DE17530524D5FE606CAE837@EXMBX1.tmwsystems.com |
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Lists: | pgsql-performance |
> An unrestricted update will end up rewriting the whole table.
> It's advisable to run VACUUM afterward, so that the wasted
> space can be reclaimed. What version are you on? Do you have
> autovacuum enabled?
>
> Also, to take a step back, why do you try to keep the
> timestamps changing like that? Why not store the information
> you need in the record (e.g. insert time as well as the
> datum) and then compute the result you need using a SELECT
> (or make it a view for convenience)? Fundamentally, these
> records aren't changing, you are just trying to interpret
> them in the context of the current day. That should be done
> using a SELECT, not an UPDATE.
>
I like Jeff's idea of redefining the problem. If you need the data to contain dates in the last 30 days, you might want to consider storing an interval, then using a view that includes a calculation using CURRENT_DATE().
Regards,
Paul Bort
Systems Engineer
TMW Systems, Inc.
pbort(at)tmwsystems(dot)com
216 831 6606 x2233
216 8313606 (fax)
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