| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Greg Stark <stark(at)enterprisedb(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, "jd(at)commandprompt(dot)com" <jd(at)commandprompt(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Greg Smith <gsmith(at)gregsmith(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: benchmarking the query planner |
| Date: | 2008-12-12 18:18:02 |
| Message-ID: | 1229105882.8673.74.camel@ebony.2ndQuadrant |
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| Lists: | pgsql-hackers |
On Fri, 2008-12-12 at 18:01 +0000, Greg Stark wrote:
> I think you need to find two different formulas, one which represents
> a clustered table and one which represents randomly distributed data.
> Then you need a way to measure just how clustered the data is so you
> know how much weight to give each formula. Perhaps comparing the
> number of duplicates in whole-block samples versus overall random
> selections would give that measure.
Please read the Chaudhuri paper.
--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support
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