Re: Postgresql 8.3 statistic stadistinct value dead wrong even with default_statistics_target=1000

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От Ron Mayer
Тема Re: Postgresql 8.3 statistic stadistinct value dead wrong even with default_statistics_target=1000
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Msg-id 48B8B993.7040704@cheapcomplexdevices.com
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Ответ на Re: Postgresql 8.3 statistic stadistinct value dead wrong even with default_statistics_target=1000  (Tom Lane <tgl@sss.pgh.pa.us>)
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Tom Lane wrote:
> Maxim Boguk <mboguk@masterhost.ru> writes:
>> [ ndistinct estimates way off ]
>
> Estimating the number of distinct values in a distribution with a long
> tail is just a really hard problem :-(

If I have a table where I know it has this property, is there
any way I can tell autovacuum's ANALYZE to go ahead and scan
the whole table?    ISTM a vacuum_cost_delay throttled full
table scan might be less harmful then a bad ndistinct guess.


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