Re: 7.2.1 optimises very badly against 7.2

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От Tom Lane
Тема Re: 7.2.1 optimises very badly against 7.2
Дата
Msg-id 26758.1026161056@sss.pgh.pa.us
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Ответ на 7.2.1 optimises very badly against 7.2  ("Sam Liddicott" <sam.liddicott@ananova.com>)
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"Sam Liddicott" <sam.liddicott@ananova.com> writes:
>> Indeed.  What do 7.2 and 7.2.1 have in the pg_stats row for
>> broadcast.channelregionid?  What is the real distribution of that
>> column?

> 7.2 says:
> [snip]

Well, that's annoying: the new ANALYZE code is in fact more accurate
than the old (it's estimating 429 distinct values, vs. formerly 4532,
when the true figure is 636) but it's nonetheless making a worse final
choice of plan.

If you turn off enable_seqscan, what EXPLAIN results do you get from
7.2.1?  How about if you leave enable_seqscan on, but reduce
random_page_cost from the default 4.0 to perhaps 3.0?

            regards, tom lane



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