Re: index usage

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: "scott.marlowe" <scott.marlowe@ihs.com>
Cc: Stephan Szabo <sszabo@megazone.bigpanda.com>, brad-pgperf@duttonbros.com, pgsql-performance@postgresql.org
Date: 2004-04-28T16:41:40Z
Lists: 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