Re: index / sequential scan problem
От
Paul Thomas
Тема
Re: index / sequential scan problem
Дата
Msg-id
20030717111248.C27264@bacon
Ответ на
index / sequential scan problem (Fabian Kreitner)
Список
Дерево обсуждения
index / sequential scan problem Fabian Kreitner <fabian.kreitner@ainea-ag.de>
Re: index / sequential scan problem Paul Thomas <paul@tmsl.demon.co.uk>
Re: index / sequential scan problem Fabian Kreitner <fabian.kreitner@ainea-ag.de>
Re: index / sequential scan problem Paul Thomas <paul@tmsl.demon.co.uk>
Re: index / sequential scan problem Fabian Kreitner <fabian.kreitner@ainea-ag.de>
Re: index / sequential scan problem Jord Tanner <jord@indygecko.com>
Re: index / sequential scan problem Paul Thomas <paul@tmsl.demon.co.uk>
Re: index / sequential scan problem Tom Lane <tgl@sss.pgh.pa.us>
Re: index / sequential scan problem "Shridhar Daithankar" <shridhar_daithankar@persistent.co.in>
Re: index / sequential scan problem Tom Lane <tgl@sss.pgh.pa.us>
Re: index / sequential scan problem Fabian Kreitner <fabian.kreitner@ainea-ag.de>
Re: index / sequential scan problem Fabian Kreitner <fabian.kreitner@ainea-ag.de>
Re: index / sequential scan problem Dennis Björklund <db@zigo.dhs.org>
Re: index / sequential scan problem Tom Lane <tgl@sss.pgh.pa.us>
Re: index / sequential scan problem "scott.marlowe" <scott.marlowe@ihs.com>
Re: index / sequential scan problem Dennis Björklund <db@zigo.dhs.org>
Re: index / sequential scan problem "Shridhar Daithankar" <shridhar_daithankar@persistent.co.in>
Re: index / sequential scan problem Fabian Kreitner <fabian.kreitner@ainea-ag.de>
Re: index / sequential scan problem "Shridhar Daithankar" <shridhar_daithankar@persistent.co.in>
On 17/07/2003 10:01 Fabian Kreitner wrote: Hi Fabian, When you are doing these kinds of tests, you need to be aware that the kernel may have most of your data cached after the first query and this may be why the second query appears to run faster. Also don't be worried if the planner chooses a seq scan for small tables as the whole table can often be bought into memory with one IO whereas reading the index then the table would be 2 IOs. HTH -- Paul Thomas +------------------------------+---------------------------------------------+ | Thomas Micro Systems Limited | Software Solutions for the Smaller Business | | Computer Consultants | http://www.thomas-micro-systems-ltd.co.uk | +------------------------------+---------------------------------------------+
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