pg.ddx.io pgsql-performance@postgresql.org mailing list archive
help / color / mirror / Atom feedlocal selectivity estimation - computing frequency of predicates
2+ messages / 2 participants
[nested] [flat]
* local selectivity estimation - computing frequency of predicates
@ 2007-04-13 08:59 Avdhoot Kishore Saple <Avdhoot_Saple@infosys.com>
2007-04-13 14:13 ` Re: local selectivity estimation - computing frequency of predicates Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 1 reply; 2+ messages in thread
From: Avdhoot Kishore Saple @ 2007-04-13 08:59 UTC (permalink / raw)
To: pgsql-performance
Dear All.
How to compute the frequency of predicate (e.g. Salary > $70000) in an
SQL query from a DB's pre-defined indexes?". I'm specifically looking at
how to retrieve information about indices (like number of pages at each
level of index, range of attribute values etc.)
Any suggestions regarding the same would be great
Thanks,
Avdhoot K. Saple
Junior Research Associate
High Performance & Grid Computing
Infosys Technologies Ltd., Bangalore
**************** CAUTION - Disclaimer *****************
This e-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended solely for the use of the addressee(s). If you are not the intended recipient, please notify the sender by e-mail and delete the original message. Further, you are not to copy, disclose, or distribute this e-mail or its contents to any other person and any such actions are unlawful. This e-mail may contain viruses. Infosys has taken every reasonable precaution to minimize this risk, but is not liable for any damage you may sustain as a result of any virus in this e-mail. You should carry out your own virus checks before opening the e-mail or attachment. Infosys reserves the right to monitor and review the content of all messages sent to or from this e-mail address. Messages sent to or from this e-mail address may be stored on the Infosys e-mail system.
***INFOSYS******** End of Disclaimer ********INFOSYS***
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: local selectivity estimation - computing frequency of predicates
2007-04-13 08:59 local selectivity estimation - computing frequency of predicates Avdhoot Kishore Saple <Avdhoot_Saple@infosys.com>
@ 2007-04-13 14:13 ` Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 0 replies; 2+ messages in thread
From: Tom Lane @ 2007-04-13 14:13 UTC (permalink / raw)
To: Avdhoot Kishore Saple <Avdhoot_Saple@infosys.com>; +Cc: pgsql-performance
"Avdhoot Kishore Saple" <Avdhoot_Saple@infosys.com> writes:
> How to compute the frequency of predicate (e.g. Salary > $70000) in an
> SQL query from a DB's pre-defined indexes?". I'm specifically looking at
> how to retrieve information about indices (like number of pages at each
> level of index, range of attribute values etc.)
I don't think what you're looking for is exposed anywhere. Postgres
doesn't rely on indexes for statistical information anyway; the
pg_statistic system catalog (see also pg_stats view) is used for that.
regards, tom lane
^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2007-04-13 14:13 UTC | newest]
Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2007-04-13 08:59 local selectivity estimation - computing frequency of predicates Avdhoot Kishore Saple <Avdhoot_Saple@infosys.com>
2007-04-13 14:13 ` Tom Lane <tgl@sss.pgh.pa.us>
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox