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От | Илья Конюхов |
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Тема | ... |
Дата | |
Msg-id | E1EU3wZ-000Fgr-00.ilyakon-mail-ru@f21.mail.ru обсуждение исходный текст |
Ответы |
Re:
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Список | pgsql-sql |
> For example, consider the queres: > > SELECT * FROM table1 WHERE field1=1 AND field2=1; > > SELECT * FROM table1 WHERE field2=1 AND field1=1; > > > These two queries are logically equivalent. But in all cases the planner generates a query plan that performs field1=1condition, and then field2=1 condition, as there is a index on field1. > > Is it possible to instruct the PostgreSQL query planner to perform field2=1 condition first, and then field1=1 condition? > > ---------------------------(end of broadcast)--------------------------- > TIP 6: explain analyze is your friend > EXPLAIN [ ANALYZE ] [ VERBOSE ] statement This command displays the execution plan that the PostgreSQL planner generates for the supplied statement. This command displays plan ONLY! But I want to instruct the PostgreSQL query planner to perform field2=1 condition first,and then field1=1 condition.
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