Re: [GENERAL] How does Postgres estimate the memory needed forsorting/aggregating

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От John R Pierce
Тема Re: [GENERAL] How does Postgres estimate the memory needed forsorting/aggregating
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Msg-id 5610e7aa-c7c9-0db2-0c37-527920046810@hogranch.com
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Ответ на [GENERAL] How does Postgres estimate the memory needed for sorting/aggregating  (Thomas Kellerer <spam_eater@gmx.net>)
Ответы Re: [GENERAL] How does Postgres estimate the memory needed forsorting/aggregating  (Tomas Vondra <tomas.vondra@2ndquadrant.com>)
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On 1/25/2017 12:59 PM, Thomas Kellerer wrote:
> So here is my question: how does Postgres estimate/know the memory
> needed for the aggregation? Or does it dynamically resize the memory
> if the initial assumption was wrong?

my understanding is it fits as much as it can into a work_mem sized
allocation, and if thats not enough uses temporary files and multiple
passes.


--
john r pierce, recycling bits in santa cruz

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