Re: Abbreviated keys for text cost model fix

From: Jeremy Harris <jgh(at)wizmail(dot)org>
To: Peter Geoghegan <pg(at)heroku(dot)com>
Cc: Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Abbreviated keys for text cost model fix
Date: 2015-02-25 09:05:30
Message-ID: 54ED905A.2070504@wizmail.org
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On 25/02/15 00:42, Peter Geoghegan wrote:
> On Tue, Feb 24, 2015 at 4:32 PM, Jeremy Harris <jgh(at)wizmail(dot)org> wrote:
>> On 23/02/15 16:40, Tomas Vondra wrote:
>>> On 22.2.2015 22:30, Peter Geoghegan wrote:
>>>> You should try it with the data fully sorted like this, but with one
>>>> tiny difference: The very last tuple is out of order. How does that
>>>> look?
>>
>> If this case is actually important, a merge-sort can take
>> significant advantage of the partial order:
>
>> test=# set enable_intmerge_sort to on;
>
> What is this?

Associated with an implementation of an internal merge sort,
a control to disable it. Not in the mainline sourcebase.
--
Cheers,
Jeremy

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