Re: index usage - Mailing list pgsql-performance

From Tom Lane
Subject Re: index usage
Date
Msg-id 424.1083170500@sss.pgh.pa.us
Whole thread Raw
In response to Re: index usage  ("scott.marlowe" <scott.marlowe@ihs.com>)
List pgsql-performance
"scott.marlowe" <scott.marlowe@ihs.com> writes:
> There are tons of hints that it works this way in how they're written, but
> nothing that just comes out and says that with pgsql's mvcc
> implementation, an index scan still has to hit the pages that contain the
> tuples, so often in pgsql a seq scan is a win where in other databases and
> index scan would have been a win?

> If not, where would I add it if I were going to write something up for the
> docs?  Just wondering...

AFAIR the only place in the docs that mentions seqscan or indexscan at
all is the discussion of EXPLAIN in "Performance Tips".  Perhaps a
suitably-enlarged version of that section could cover this.

            regards, tom lane

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