| From: | "Vladimir Sitnikov" <sitnikov(dot)vladimir(at)gmail(dot)com> |
|---|---|
| To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| 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 18:53:35 |
| Message-ID: | 1d709ecc0812111053l5b11483fpb29474687583bfbe@mail.gmail.com |
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| Lists: | pgsql-hackers |
>
>
> BTW, does anyone have an opinion about changing the upper limit for
> default_stats_target to, say, 10000? These tests suggest that you
> wouldn't want such a value for a column used as a join key, but
> I can see a possible argument for high values in text search and
> similar applications.
>
Do you consider using hash tables?
I am not sure hash is a perfect match here, however I guess some kind of
data structure might improve N^2 behaviour. Looks like that would improve
both array_eq (that will narrow the list of possible arrays to the single
hash bucket) and large _target (I guess that would improve N^2 to N)
Regards,
Vladimir Sitnikov
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