Re: [HACKERS] Much Ado About COUNT(*) - Mailing list pgsql-general

From Richard Huxton
Subject Re: [HACKERS] Much Ado About COUNT(*)
Date
Msg-id 41E81198.6070105@archonet.com
Whole thread Raw
In response to Re: [HACKERS] Much Ado About COUNT(*)  ("Frank D. Engel, Jr." <fde101@fjrhome.net>)
List pgsql-general
Frank D. Engel, Jr. wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> 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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