Search Postgresql Archives

index usage in joins q'n

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



http://www.postgresql.org/docs/8.2/interactive/indexes-intro.html
states that "Indexes can moreover be used in join searches. Thus, an index defined on a column that is part of a join condition can significantly speed up queries with joins."

Does this mean that a condition like "WHERE ... [AND] lhs.a=rhs.b [AND] ..." where rhs.b is already unique-indexed, also requires (non-unique) index on lhs.a for maximal join speed? Otherwise why would they want to say that?

Thanks.

---------------------------(end of broadcast)---------------------------
TIP 1: if posting/reading through Usenet, please send an appropriate
      subscribe-nomail command to majordomo@xxxxxxxxxxxxxx so that your
      message can get through to the mailing list cleanly

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux