Re: Slow HashAggregate/cache access

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От David Rowley
Тема Re: Slow HashAggregate/cache access
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Msg-id CAKJS1f_njtJrXb32m910qx0YcMzjGivRNRthKJ4bVROki686Kg@mail.gmail.com
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Ответ на Re: Slow HashAggregate/cache access  (Andreas Joseph Krogh <andreas@visena.com>)
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On 6 August 2015 at 07:55, Andreas Joseph Krogh <andreas@visena.com> wrote:
På onsdag 05. august 2015 kl. 20:25:25, skrev Maxim Boguk <maxim.boguk@gmail.com>:
[snip]
 
​I think I know where issue is.
The PostgreSQL planner unable pass join conditions into subquery with aggregate functions (it's well known limitation).
[snip]
 
I'm curious; will 9.5 help here as it has "WHERE clause pushdown in subqueries with window functions"?
 


I've not looked at the query in any detail, but that particular patch won't help as it only allows pushdown of predicate into subqueries with window functions where the predicate is part of all of the subquery's PARTITION BY clauses.

The query in question has no window clauses, so qual pushdown is not disabled for that reason. 

Regards

David Rowley
--
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services
 

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