Re: JOINS and non use of indexes
От | Christopher Kings-Lynne |
---|---|
Тема | Re: JOINS and non use of indexes |
Дата | |
Msg-id | 003401c1df0a$523bead0$0200a8c0@SOL обсуждение исходный текст |
Ответ на | JOINS and non use of indexes ("Ian Cass" <ian.cass@mblox.com>) |
Список | pgsql-sql |
I haven't had a good look, but just remember that indexes on a table in postgres are NOT inherited by its children. You cannot define a unique index over a column that is inherited - it will be unique for the table you define it on only. Hence, you may not actually have indexes on those inherited tables, and therefore they cannot be used... Chris > Explain plan.... > Limit (cost=0.00..35.06 rows=5 width=620) > -> Nested Loop (cost=0.00..30986063.51 rows=4418898 width=620) > -> Append (cost=0.00..441.93 rows=111 width=496) > -> Seq Scan on messages (cost=0.00..0.00 rows=1 width=496) > -> Index Scan using messages_200203_ix2 on messages_200203 messages > (cost=0.00..272.61 rows=68 width=383) > -> Index Scan using messages_200204_ix2 on messages_200204 messages > (cost=0.00..169.32 rows=42 width=384) > -> Append (cost=0.00..180413.11 rows=7996912 width=124) > -> Seq Scan on statusinds (cost=0.00..0.00 rows=1 width=124) > -> Seq Scan on statusinds_200203 statusinds (cost=0.00..142835.73 > rows=6292073 width=71) > -> Seq Scan on statusinds_200204 statusinds (cost=0.00..37577.38 > rows=1704838 width=65) > > (tables_YYYYMM are inherited) > > -- > Ian Cass > > > ---------------------------(end of broadcast)--------------------------- > TIP 4: Don't 'kill -9' the postmaster >
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