Will an outer join on two indexed fields use the indexes?
От | Nick Fankhauser |
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Тема | Will an outer join on two indexed fields use the indexes? |
Дата | |
Msg-id | NEBBLAAHGLEEPCGOBHDGOEKCELAA.nickf@ontko.com обсуждение исходный текст |
Ответы |
Re: Will an outer join on two indexed fields use the indexes?
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Список | pgsql-admin |
Hi- I've got another "plan" question- I'm trying to tune a query that uses an outer join on two indexed (not unique) fields. I did an explain on it & was surprised to find that the index wasn't used: monroe=# explain select * from monroe-# (charge left outer join criminal_disposition on monroe(# (charge.charge_id = criminal_disposition.charge_id)); NOTICE: QUERY PLAN: Hash Join (cost=260.68..21110.40 rows=147101 width=360) -> Seq Scan on charge (cost=0.00..4883.01 rows=147101 width=252) -> Hash (cost=150.94..150.94 rows=5894 width=108) -> Seq Scan on criminal_disposition (cost=0.00..150.94 rows=5894 width=108) My question is- Does the fact that this is an outer join cause this, or is soem other factor involved? If it is the outer join, is there a different way to join these which will be more efficient? Thanks! -Nick -------------------------------------------------------------------------- Nick Fankhauser nickf@ontko.com Phone 1.765.935.4283 Fax 1.765.962.9788 Ray Ontko & Co. Software Consulting Services http://www.ontko.com/
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