From: Mikhail Yakshin <greycat@altlinux.org> To: ALT Linux Team development discussions <devel@lists.altlinux.org> Subject: Re: [devel] Mysqld CPU usage at www.sisyphus.ru Date: Tue, 1 Sep 2009 19:03:00 +0400 Message-ID: <240e377b0909010803p309ef97dxcb8ad8bf31b1d453@mail.gmail.com> (raw) In-Reply-To: <20090901184953.710824a4@bga> >> тогда запрос и explain от него - в студию. > > Вот такие запросы тормозят: > > SELECT DISTINCT s.name, s.version, s.rel, m.packager, s.summary, s.repo > FROM srpm as s, maintainers as m, rpm as r WHERE r.srpm = s.name AND > m.mail=s.packager AND ( s.name RLIKE 'unichrome' OR s.summary RLIKE > 'unichrome' OR s.description RLIKE 'unichrome' OR r.namen RLIKE > 'unichrome' ) AND s.repo='Sisyphus' AND r.repo='Sisyphus' ORDER BY 1 > ASC LIMIT 0,20; > > Может быть, заменить RLIKE на MATCH AGAINST ? Будет быстрее? Во-первых, проверить индексы, по которым производится JOIN. Имеет смысл выписать это в явный "INNER JOIN ON что-то": > WHERE r.srpm = s.name AND m.mail=s.packager Во-вторых, такой RLIKE скорее всего вообще не использует индексы и запрос превращается в FULL SCAN. Проверить индексы, по которым делается RLIKE и заменить его либо на LIKE 'запрос%', либо на равенство. MATCH AGAINST потребует полнотекстовых индексов, да и будет возвращать совсем не то, что хочется, как я понял. -- WBR, Mikhail Yakshin
next prev parent reply other threads:[~2009-09-01 15:03 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-09-01 13:08 Grigory Batalov 2009-09-01 13:10 ` Alexey I. Froloff 2009-09-01 13:11 ` Alex Gorbachenko 2009-09-01 13:32 ` Grigory Batalov 2009-09-01 13:40 ` Alex Gorbachenko 2009-09-01 14:49 ` Grigory Batalov 2009-09-01 15:03 ` Mikhail Yakshin [this message] 2009-09-01 19:20 ` Grigory Batalov 2009-09-01 19:21 ` Aleksey Avdeev 2009-09-01 20:27 ` Grigory Batalov 2009-09-01 21:47 ` Mikhail Yakshin 2009-09-02 1:16 ` Денис Смирнов 2009-09-02 4:35 ` Mikhail Yakshin 2009-09-01 13:12 ` Michael Shigorin 2009-09-01 16:36 ` Vitaly Lipatov 2009-09-01 20:49 ` Денис Смирнов
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