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Re: Aggregate and many LEFT JOIN - Mailing list pgsql-performance

From kimaidou
Subject Re: Aggregate and many LEFT JOIN
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Msg-id CAMKXKO5qvnLYCYRJux4yaN=Lj-phCgnE+KBere7VS7d31z78JA@mail.gmail.com
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In response to Re: Aggregate and many LEFT JOIN  (Michael Lewis <mlewis@entrata.com>)
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I manage to avoid the disk sort after performing a VACUUM ANALYSE;
And with a session work_mem = '250MB'


It stills spent 16s
It seems this kind of query will need better hardware to scale...

Thanks for your help


Le lun. 25 févr. 2019 à 19:30, Michael Lewis <mlewis@entrata.com> a écrit :


On Mon, Feb 25, 2019 at 2:44 AM kimaidou <kimaidou@gmail.com> wrote:
I have better results with this version. Basically, I run a first query only made for aggregation, and then do a JOIN to get other needed data.


Not really "fast", but I gained 30%
 

It still seems that disk sort and everything after that is where the query plan dies. It seems odd that it went to disk if work_mem was already 250MB. Can you allocate more as a test? As an alternative, if this is a frequently needed data, can you aggregate this data and keep a summarized copy updated periodically?

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