Re: Re: custom hash-based COUNT(DISTINCT) aggregate - unexpectedly high memory consumption - Mailing list pgsql-hackers

From Tomas Vondra
Subject Re: Re: custom hash-based COUNT(DISTINCT) aggregate - unexpectedly high memory consumption
Date
Msg-id 5134df4261525cabdf51b505be5bbaf2.squirrel@sq.gransy.com
Whole thread Raw
In response to Re: Re: custom hash-based COUNT(DISTINCT) aggregate - unexpectedly high memory consumption  (Atri Sharma <atri.jiit@gmail.com>)
Responses Re: Re: custom hash-based COUNT(DISTINCT) aggregate - unexpectedly high memory consumption  (Atri Sharma <atri.jiit@gmail.com>)
List pgsql-hackers
On 8 Říjen 2013, 11:42, Atri Sharma wrote:
>>
>> I've made some significant improvements in the chaining version (in the
>> master branch), now getting about the memory consumption I've estimated.
>>
> I agree, we can hope to reduce the memory consumption by making changes in
> the current chaining implementation. I would like to look into changing
> the data structure used for chaining from singly linked list to maybe skip
> list or something else.

Just to be sure - I haven't been messing with the HashAggregate
implementation directly, but with a custom aggregate. But feel free to
tweak the built-in hash table ;-)

Tomas




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