| From: | "Christopher Kings-Lynne" <chriskl(at)familyhealth(dot)com(dot)au> |
|---|---|
| To: | "mlw" <markw(at)mohawksoft(dot)com>, "Bruce Momjian" <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Louis-David Mitterrand" <vindex(at)apartia(dot)org>, <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Index Scans become Seq Scans after VACUUM ANALYSE |
| Date: | 2002-04-17 05:42:34 |
| Message-ID: | GNELIHDDFBOCMGBFGEFOMECMCCAA.chriskl@familyhealth.com.au |
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| Thread: | |
| Lists: | pgsql-hackers |
> I have bitched about the index stuff for a while, and always have
> bumped up
> against this problem. If I can sway anyone's opinion, I would say, unless
> (using Tom's words) a "factor of 2" planner difference against, I
> would use an
> index. Rather than needing clear evidence to use an index, I
> would say you need
> clear evidence not too.
I spend a lot of time answering questions on various database forums and I
find that the single thing that most newbies just cannot understand is that
a sequential scan is often a lot faster than an index scan. They just
cannot comprehend that an index can be slower. Ever. For any query. That
is not our problem...
What we could offer tho, is more manual control over the planner. People
can do this to a mild extend by disabling sequential scans, but it looks
like it should be extended...
Chris
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