Re: Disappointing performance in db migrated from MS SQL Server
От | Josh Berkus |
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Тема | Re: Disappointing performance in db migrated from MS SQL Server |
Дата | |
Msg-id | 200402121226.33823.josh@agliodbs.com обсуждение исходный текст |
Ответ на | Disappointing performance in db migrated from MS SQL Server (Leon Out <leon-lists@comvision.com>) |
Ответы |
Re: Disappointing performance in db migrated from MS SQL Server
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Список | pgsql-performance |
Leon, > Hello all. I am in the midst of porting a large web application from a > MS SQL Server backend to PostgreSQL. The migration work is basically > complete, and we're at the testing and optimization phase of the > project. The results so far have been disappointing, with Postgres > performing queries in about the same time as SQL Server even though > Postgres is running on a dedicated box with about 4 times the clock > speed of the SQL Server box. For a chart of my results, please see > http://leonout.com/pggraph.pdf for a graph of some test results. Your settings look ok to start, but we'll probably want to tune them further. Can you post some details of the tests? Include: 1) the query 2) the EXPLAIN ANALYZE results of the query 3) Whether you ran the test as the only connection, or whether you tested multi-user load. The last is fairly important for a SQL Server vs. PostgreSQL test; SQL Server is basically a single-user-database, so like MySQL it appears very fast until you get a bunch o' users on it. Finally, for most queries the disk I/O and the RAM are more important than the CPU clock speed. From the looks of it, you upgraded the CPU + RAM, but did downgraded the disk array as far as database writes are concered; not a terrible effective way to gain performance on your hardware. -- -Josh Berkus Aglio Database Solutions San Francisco
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