From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | o2(at)trustcommerce(dot)com |
Cc: | pgsql-general(at)postgreSQL(dot)org |
Subject: | Re: Index Scans Oddness |
Date: | 2001-10-12 19:47:55 |
Message-ID: | 1188.1002916075@sss.pgh.pa.us |
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Lists: | pgsql-admin pgsql-bugs pgsql-general |
Orion <o2(at)trustcommerce(dot)com> writes:
> select * from foo where text_field like 'foo%'
> will do an index scan with my data in 7.0.3 but not 7.1.3-1PGDG.
> Makes me think there's a bug.
Yes: in 7.0. You're probably running in a non-C locale, wherein
optimizing LIKE with an indexscan is unsafe.
> select * from foo where order_date = current_date
> and
> select * from foo
> where order_date < to_date(xxx) and order_date > to_date(yyy)
> Both do sequence scans where current date is indexed
The problem is probably lack of cachability of current_date and to_date().
You can fix this with a wrapper function that's marked "iscachable".
Look in the mailing list archives for prior discussions.
regards, tom lane
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