| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Andrew McMillan <Andrew(at)catalyst(dot)net(dot)nz> |
| Cc: | Matthias Urlichs <smurf(at)noris(dot)net>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: More Performance |
| Date: | 2000-05-21 01:59:04 |
| Message-ID: | 200005210159.VAA03127@candle.pha.pa.us |
| Views: | Whole Thread | Raw Message | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
> > We can't read data from the index. It would be nice if we could, but we
> > can't. I think we believe that there are very few cases where this
> > would be win. Usually you need non-indexed data too.
>
> I have used other databases where this _is_ possible in the past, and
> the win is big when the programmer codes for it. Sure, most cases don't
> just use indexed data, but if the programmer knows that the database
> supports index-only scans then sometimes an extreme performance
> requirement can be met.
>
Yes, totally true. It is an extreme optimization. In Ingres, you could
actually SELECT on the index and use that when needed.
--
Bruce Momjian | http://www.op.net/~candle
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Tom Lane | 2000-05-21 02:36:04 | Re: Re: Heaps of read() syscalls by the postmaster |
| Previous Message | Bruce Momjian | 2000-05-21 01:57:50 | Re: Performance (was: The New Slashdot Setup (includes MySql server)) |