| From: | Thomas Lockhart <lockhart(at)fourpalms(dot)org> |
|---|---|
| To: | mlw <markw(at)mohawksoft(dot)com> |
| Cc: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andrew Sullivan <andrew(at)libertyrms(dot)info>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Index Scans become Seq Scans after VACUUM ANALYSE |
| Date: | 2002-04-18 15:16:52 |
| Message-ID: | 3CBEE364.CB82408A@fourpalms.org |
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| Lists: | pgsql-hackers |
...
> My one most important experience (I've had more than one) with this whole topic
> is DMN's music database, when PostgreSQL uses the index, the query executes in
> a fraction of a second. When "enable_seqscan=true" PostgreSQL refuses to use
> the index, and the query takes a about a minute. No matter how much I analyze,
> I have to disable sequential scan for the system to work correctly.
How about contributing the data and a query? We've all got things that
we would like to change or adjust in the PostgreSQL feature set. If you
can't contribute code, how about organizing some choice datasets for
testing purposes? If the accumulated set is too big for postgresql.org
(probably not, but...) I can host them on my machine.
Most folks seem to not have to manipulate the optimizer to get good
results nowadays. So to make more progress we need to have test cases...
- Thomas
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