Re: Performance of count(*)
От
Tom Lane
Тема
Re: Performance of count(*)
Дата
Msg-id
20588.1174588646@sss.pgh.pa.us
Ответ на
Re: Performance of count(*) (Craig A. James)
Список
Дерево обсуждения
Performance of count(*) Andreas Tille <tillea@rki.de>
Re: Performance of count(*) Andreas Kostyrka <andreas@kostyrka.org>
Re: Performance of count(*) Andreas Tille <tillea@rki.de>
Re: Performance of count(*) Andreas Kostyrka <andreas@kostyrka.org>
Re: Performance of count(*) Michael Fuhr <mike@fuhr.org>
Re: Performance of count(*) Carlos Moreno <moreno_pg@mochima.com>
Re: Performance of count(*) "Luke Lonergan" <llonergan@greenplum.com>
Re: Performance of count(*) Albert Cervera Areny <albert@sedifa.com>
Re: Performance of count(*) ismo.tuononen@solenovo.fi
Re: Performance of count(*) Bill Moran <wmoran@collaborativefusion.com>
Re: Performance of count(*) Michael Stone <mstone+postgres@mathom.us>
Re: Performance of count(*) mark@mark.mielke.cc
Re: Performance of count(*) "Craig A. James" <cjames@modgraph-usa.com>
Re: Performance of count(*) Tino Wildenhain <tino@wildenhain.de>
Re: Performance of count(*) "Craig A. James" <cjames@modgraph-usa.com>
Re: Performance of count(*) Steve Atkins <steve@blighty.com>
Re: Performance of count(*) "Craig A. James" <cjames@modgraph-usa.com>
Re: Performance of count(*) Tom Lane <tgl@sss.pgh.pa.us>
Re: Performance of count(*) "Craig A. James" <cjames@modgraph-usa.com>
Re: Performance of count(*) Tom Lane <tgl@sss.pgh.pa.us>
Re: Performance of count(*) Guido Neitzer <lists@event-s.net>
Re: Performance of count(*) Steve Atkins <steve@blighty.com>
Re: Performance of count(*) Tino Wildenhain <tino@wildenhain.de>
Re: Performance of count(*) Michael Stone <mstone+postgres@mathom.us>
Re: Performance of count(*) Tino Wildenhain <tino@wildenhain.de>
Re: Performance of count(*) Michael Stone <mstone+postgres@mathom.us>
Re: Performance of count(*) Tino Wildenhain <tino@wildenhain.de>
Re: Performance of count(*) "Merlin Moncure" <mmoncure@gmail.com>
Re: Performance of count(*) Tino Wildenhain <tino@wildenhain.de>
Re: Performance of count(*) Michael Stone <mstone+postgres@mathom.us>
Re: Performance of count(*) Michael Stone <mstone+postgres@mathom.us>
Re: Performance of count(*) Michael Stone <mstone+postgres@mathom.us>
Re: Performance of count(*) "Craig A. James" <cjames@modgraph-usa.com>
Re: Performance of count(*) Tino Wildenhain <tino@wildenhain.de>
Re: Performance of count(*) Brian Hurt <bhurt@janestcapital.com>
Re: Performance of count(*) "Craig A. James" <cjames@modgraph-usa.com>
Re: Performance of count(*) Mario Weilguni <mweilguni@sime.com>
Re: Performance of count(*) "Merlin Moncure" <mmoncure@gmail.com>
Re: Performance of count(*) Michael Stone <mstone+postgres@mathom.us>
Re: Performance of count(*) "Jonah H. Harris" <jonah.harris@gmail.com>
Re: Performance of count(*) Mario Weilguni <mweilguni@sime.com>
Re: Performance of count(*) Andreas Kostyrka <andreas@kostyrka.org>
Re: Performance of count(*) Mario Weilguni <mweilguni@sime.com>
Re: Performance of count(*) ismo.tuononen@solenovo.fi
"Craig A. James" writes: > Steve Atkins wrote: >> As long as you're ordering by some row in the table then you can do that in >> straight SQL. >> >> select a, b, ts from foo where (stuff) and foo > X order by foo limit 10 >> >> Then, record the last value of foo you read, and plug it in as X the next >> time around. > We've been over this before in this forum: It doesn't work as advertised. Look for postings by me regarding the fact that there is no way to tell the optimizer the cost of executing a function. There's one, for example, on Oct 18, 2006. You mean http://archives.postgresql.org/pgsql-performance/2006-10/msg00283.php ? I don't see anything there that bears on Steve's suggestion. (The complaint is obsolete as of CVS HEAD anyway.) regards, tom lane
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