Re: Abbreviated keys for text cost model fix - Mailing list pgsql-hackers

From Jeremy Harris
Subject Re: Abbreviated keys for text cost model fix
Date
Msg-id 54ED905A.2070504@wizmail.org
Whole thread Raw
In response to Re: Abbreviated keys for text cost model fix  (Peter Geoghegan <pg@heroku.com>)
List pgsql-hackers
On 25/02/15 00:42, Peter Geoghegan wrote:
> On Tue, Feb 24, 2015 at 4:32 PM, Jeremy Harris <jgh@wizmail.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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