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List:       pgsql-hackers
Subject:    Re: [HACKERS] Inlining comparators as a performance optimisation
From:       Greg Jaskiewicz <gj () pointblue ! com ! pl>
Date:       2011-11-29 21:43:40
Message-ID: EF6F6E8D-144E-4B5B-9A05-33BF8EC04C65 () pointblue ! com ! pl
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On 28 Nov 2011, at 02:15, Peter Geoghegan wrote:

> Attached are the results from performing a similar process to the
> prior benchmark, but on Greg Smith's high-end server, and with an
> orderlines table that has been "doubled-up" until it is 1538 MB,
> making the same old query perform a quicksort that's over 3GB. Short
> version:  HEAD is 20468.0ms, with my patch it's 13689.698ms, so these
> gains hold-up very well for very large in-memory sorts, possibly even
> perfectly.
> 

This is some really good stuff. 
Has to be said, that there must be quite few other places where inlining like that \
could have quite a positive benefit.  But - I also have to say that both template \
functions and template classes in C++ give you pretty much the same speed \
improvement, with much better clarity and readability of the code. (I've tested it \
with the example Peter presented, if someone is interested in the code).  One more \
reason why PostgreSQL project should look into the future and get some of the bits \
simplified and optimised by switching to C++. 




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