| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Vladimir Sitnikov" <sitnikov(dot)vladimir(at)gmail(dot)com> |
| Cc: | "Robert Haas" <robertmhaas(at)gmail(dot)com>, "Gregory Stark" <stark(at)enterprisedb(dot)com>, "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: | 2008-12-11 21:28:28 |
| Message-ID: | 11419.1229030908@sss.pgh.pa.us |
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"Vladimir Sitnikov" <sitnikov(dot)vladimir(at)gmail(dot)com> writes:
> One more direction could be implementing "MCV" for range of values (group
> values and interpolate in between). Consider statistics on timestamp column
> that says that for "2008-December" there are as many X rows, for
> "2008-November" as many as Y, etc. That could be used for rather accurate
> cardinality estimation of "between" cases, while keeping number of entries
> in "MCV" list small.
I think that would likely be redundant with the histogram.
regards, tom lane
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