Re: for help!

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От Andrew Sullivan
Тема Re: for help!
Дата
Msg-id 20030416155312.GF19999@libertyrms.info
обсуждение исходный текст
Ответ на Re: for help!  (Josh Berkus <josh@agliodbs.com>)
Ответы Re: for help!  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-performance
On Wed, Apr 16, 2003 at 08:48:36AM -0700, Josh Berkus wrote:
> Scott,
>
> > Well, you can always use the trick of putting an on insert / delete
> > trigger on the table that maintains a single row table with the current
> > count.  That way, whenever a row is added or removed, the count is

> BTW, I tested this for a client.   I found the performance penalty
> on inserts and updates to be:

[. . .]

> Please note that the effective performance penalty on inserts and
> updates was dramatically higher for large batches of updates than
> for small ones.

Presumably the problem was to do with contention?  This is why I
don't really like the "update one row" approach for this sort of
thing.

But you _could_ write a trigger which inserts into a "staging" table,
and write a little daemon which only updates the count table with the
data from the staging table.  It's a mighty ugly hack, but it ought
to work.

A

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Andrew Sullivan                         204-4141 Yonge Street
Liberty RMS                           Toronto, Ontario Canada
<andrew@libertyrms.info>                              M2P 2A8
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