Re: Built-in binning functions

From: Petr Jelinek <petr(at)2ndquadrant(dot)com>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Built-in binning functions
Date: 2014-07-18 12:34:58
Message-ID: 53C91472.6020108@2ndquadrant.com
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On 16/07/14 21:35, Pavel Stehule wrote:
> The performance difference is about 20% (+/- few depending on the
> array size), I don't know if that's bad enough to warrant
> type-specific implementation. I personally don't know how to make
> the generic implementation much faster than it is now, except maybe
> by turning it into aggregate which would cache the deconstructed
> version of the array, but that change semantics quite a bit and is
> probably not all that desirable.
>
>
> I am not sure if our API is enough to do it - there are no any simple
> support for immutable parameters.

Just to clarify, the ~20% performance difference is with separate
generic implementation for fixed width types (most of the time seems to
be spent in the FunctionCallInvoke part, I even tryed to use sortsupport
instead but it does not seem to help much).

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

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