On 07/10/2012 06:24 AM, Misa Simic wrote:
Hi Andrew,
Sure... We are sending data in Json to clients
{
total:6784,
data:[50 rows for desired page]
}
SELECT count(*) FROM table - without where, without joins used to have
bad performance... However, in real scenario we have never had the case
without joins and where... Join columns are always indexed, and we
always try to put indexes on columns what will mostly be used in where
in usual queries...
When/if you do need a count of a single table without any filters, a
common trick is to use table statistics to return an approximation. If
your autovaccum is running regularly it's usually a very good
approximation, too.
Sounds like this hack may become unnecessary in 9.2 though.
--
Craig Ringer
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