| From: | Pierre-Frédéric Caillaud <lists(at)boutiquenumerique(dot)com> |
|---|---|
| To: | "Madison Kelly" <linux(at)alteeve(dot)com>, "PgSQL General List" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Question on a select |
| Date: | 2005-01-02 15:45:45 |
| Message-ID: | opsjzfejkwcq72hf@musicbox |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
> I didn't realize that the order made a difference. A sign of how much
> learning I need to do. :p For reference, I think 'file_parent_dir' and
> 'fs_parent_dir' are the most important because I do an 'ORDER BY
> [fs|file]_parent_dir ASC' on most queries. I've made the changes, thank
> you again!
If you SELECT ... WHERE condition on A order by B :
an index on A will be used, but an index on B won't
If you SELECT ... WHERE condition on A order by A, B :
an index on A,B will be used because it will give the rows in already
sorted order
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