| From: | Richard Huxton <dev(at)archonet(dot)com> |
|---|---|
| To: | "Frank D(dot) Engel, Jr(dot)" <fde101(at)fjrhome(dot)net> |
| Cc: | Postgres general mailing list <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Much Ado About COUNT(*) |
| Date: | 2005-01-14 18:38:16 |
| Message-ID: | 41E81198.6070105@archonet.com |
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| Lists: | pgsql-general pgsql-hackers |
Frank D. Engel, Jr. wrote:
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>
> This is probably stupid for some reason, but why not use a 64-bit
> integer to track the number of records in the table? Increment when
> adding records, decrement when deleting them... then COUNT(*) could just
> return that in cases where a query is known to be looking at all of the
> records?
Check the list archives for details, but you need to consider multiple
backends inserting/deleting concurrently. What you need is a separate
little table where you can log your transaction-id and number of rows
added/removed then you can figure out how many rows there are from
different viewpoints.
--
Richard Huxton
Archonet Ltd
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