Re: MySQL 5 comparison
От | Hans-Jürgen Schönig |
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Тема | Re: MySQL 5 comparison |
Дата | |
Msg-id | 41DE5D0E.1040009@cybertec.at обсуждение исходный текст |
Ответ на | Re: MySQL 5 comparison (Robert Treat <xzilla@users.sourceforge.net>) |
Ответы |
Re: MySQL 5 comparison
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Список | pgsql-advocacy |
Robert Treat wrote: > On Thu, 2005-01-06 at 05:03, Hans-Jürgen Schönig wrote: > >>For all those who think of comparing PostgreSQL - maybe this story >>should be added. >>I HAD to do benchmark a benchmark comparing MySQL and Slony replication. >> >>a. if you create a table as Innodb it MIGHT become ISAM without warning >>(depending on a nicely hidden config parameter). >>b. it seems as if BEGIN / COMMIT are silently accepted in ISAM tables ... >>c. when dumping a master database it will not necessarily restore on the >>slave database; we got a primary key violation on a unique >>column a couple of times. >>d. then we did a replication scenario: >> >>lucent@schankserver:~/replication_tests/query$ cat 05.sql >>BEGIN; >>UPDATE t_one SET intvalue = id WHERE id = 'RANDOMINT'; >>UPDATE t_one SET intvalue = id WHERE id = 'RANDOMINT'; >>COMMIT; >> >>BEGIN; >>DELETE FROM t_one WHERE id = 'RANDOMINT'; >>ROLLBACK; >> >>myisam -> innodb replication: >>when doing this script above (30 concurrent users, 50 runs / user) >> >> >>After the run PostgreSQL still had 500.000 records in the table - mysql >>had only 499.950 (rest was ignored because MyISAM cannot do rollback). >>But if I do 30 user * 50 runs = 1500 delete statements; why do only 50 >>records miss? >> >>What do you think? Is a database allowed to eat data and issue as >>WARNING instead of a hyper-fatal error? >> >>MySQL benchmark with replication; 2 concurrent users; 10000 repetitions >>real 2m06.893s >> >>MySQL benchmark with replication; 40 concurrent users; 500 repetitions >>real 6m40.474s >> >>In case of just two concurrent users MySQL is truly fast – it is very >>unlikely that two users will hit the same random data area. However, the >>situation changes dramatically when the number of concurrent users is >>risen. Although we execute the same number of statements MySQL will be 2 >>½ times slower (with Innodb). In case of MyISAM we have seen MySQL being >>5 times slower than PostgreSQL. >>PostgreSQL with replication; 2 concurrent users; 10000 repetitions >>real 2m4.317s >>PostgreSQL with replication; 40 concurrent users; 500 repetitions >>real 2m53.324s >> >>In contrast to MySQL, PostgreSQL will perform really well in case of >>multiple concurrent users. The time needed is increasing but those >>changes are not that dramatical. We think that at least 10 seconds could >>be shaved off by doing further tweaks inside the background writer process. >> >> >> >>Any more questions? Is it still worth to compare? I think we can agree >>that MySQL is crap ... >> > > > Mind if i ask which versions of postgresql(&slony)/my$ql these were > tested against and on what OS ? > > Robert Treat We used PostgreSQL 8.0 RC3 and MySQL Debian packages (MySQL 4.0.22). OS: Debian Linux on Amd Athlon. Best regards, Hans -- Cybertec Geschwinde u Schoenig Schoengrabern 134, A-2020 Hollabrunn, Austria Tel: +43/660/816 40 77 www.cybertec.at, www.postgresql.at
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