Re: Abbreviated keys for Numeric

From: "ktm(at)rice(dot)edu" <ktm(at)rice(dot)edu>
To: Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>
Cc: Peter Geoghegan <pg(at)heroku(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz>
Subject: Re: Abbreviated keys for Numeric
Date: 2015-03-24 13:00:20
Message-ID: 20150324130020.GA28249@aart.rice.edu
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On Mon, Mar 23, 2015 at 09:41:40PM +0000, Andrew Gierth wrote:
> >>>>> "Peter" == Peter Geoghegan <pg(at)heroku(dot)com> writes:
>
> Peter> As I said, I don't really consider that my patch is a rewrite,
> Peter> especially V4, which changes nothing substantive except removing
> Peter> 32-bit support.
>
> Well, that's a hell of an "except".
>
> Here's my main arguments for why 32bit support should be kept:
>
> 1. It exists and works well (and yes, I have tested it).
>
> 2. This optimization is a huge win even on very small data sets. On
> sorts of as few as 100 items it gives detectable (on the order of +50%)
> improvements. On 1000 items the speedup can easily be 3 times. So it's
> not just people with big data who want this; even small databases will
> benefit.
>
> 3. Keeping the 32bit support (and desupporting DEC_DIGITS != 4) makes it
> unnecessary to have #ifdefs that disable the numeric abbreviation
> entirely. (You don't even need those for comparative performance
> testing; easier to do that by tweaking the catalogs.)
>
> As against that, you have the fact that it's ~70 lines of code in one
> self-contained function which is 32bit-specific.
>
> So what do other people think?
>

+1 for including 32-bit support as well. This is a tremendous performance
increase and users of older systems will benefit, and should benefit.

Regards,
Ken

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