Yet another question on LIMIT performance :/
От | Hannes Dorbath |
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Тема | Yet another question on LIMIT performance :/ |
Дата | |
Msg-id | einfmm$r41$1@news.hub.org обсуждение исходный текст |
Ответы |
Re: Yet another question on LIMIT performance :/
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Список | pgsql-performance |
Though I've read recent threads, I'm unsure if any matches my case. We have 2 tables: revisions and revisions_active. revisions contains 117707 rows, revisions_active 17827 rows. DDL: http://hannes.imos.net/ddl.sql.txt Joining the 2 tables without an additional condition seems ok for me (given our outdated hardware): http://hannes.imos.net/query_1.sql.txt What worries me is the performance when limiting the recordset: http://hannes.imos.net/query_2.sql.txt Though it should only have to join a few rows it seems to scan all rows. From experience I thought that adding an ORDER BY on the index columns should speed it up. But no effect: http://hannes.imos.net/query_3.sql.txt I'm on 8.1.5, statistics (ANALYZE) are up to date, the tables have each been CLUSTERed by PK, statistic target for the join columns has been set to 100 (without any effect). Thanks in advance! -- Regards, Hannes Dorbath
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