| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Stephen Denne" <Stephen(dot)Denne(at)datamail(dot)co(dot)nz> |
| Cc: | "Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com>, "Mark Mielke" <mark(at)mark(dot)mielke(dot)cc>, "PostgreSQL-development" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: count(*) performance improvement ideas |
| Date: | 2008-04-16 01:55:58 |
| Message-ID: | 20299.1208310958@sss.pgh.pa.us |
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"Stephen Denne" <Stephen(dot)Denne(at)datamail(dot)co(dot)nz> writes:
> The custom variable class can also be used to aggregate the deltas within a transaction, though there are some minor difficulties:
> 1) They only store text
> 2) You can only find out that a value has not been set by catching an exception
> 3) There is no way to list the settings.
As for 2) and 3), can't you look into the pg_settings view?
> The time to create them for the first time for a connection seems to
vary a bit, between 200 and 1000 per minute.
Yeah, that path is not optimized at all because it was never considered
performance-critical. Updating an existing variable should be cheaper.
regards, tom lane
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