Re: B-Tree support function number 3 (strxfrm() optimization)

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Peter Geoghegan <pg(at)heroku(dot)com>
Cc: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Noah Misch <noah(at)leadboat(dot)com>, Marti Raudsepp <marti(at)juffo(dot)org>, Stephen Frost <sfrost(at)snowman(dot)net>, Greg Stark <stark(at)mit(dot)edu>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Thom Brown <thom(at)linux(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: B-Tree support function number 3 (strxfrm() optimization)
Date: 2014-08-07 19:17:50
Message-ID: CA+TgmoZxsQzDJXJE-CgdGTSZO=7Xw_k2ukvemOdfcArbg2veVA@mail.gmail.com
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On Thu, Aug 7, 2014 at 3:15 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Wed, Aug 6, 2014 at 7:18 PM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
>> On Wed, Aug 6, 2014 at 1:11 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> I've committed the patch I posted yesterday. I did not see a good
>>> reason to meld that together in a single commit with the first of the
>>> patches you posted; I'll leave you to revise that patch to conform
>>> with this approach.
>>
>> Okay. Attached is the same patch set, rebased on top on your commit
>> with appropriate amendments.
>
> Two things:
>
> + * result. Also, since strxfrm()/strcoll() require
> NULL-terminated inputs,
>
> In my original patch, I wrote NUL, as in the NUL character. You've
> changed it to NULL, but the original was correct. NULL is a pointer
> value that is not relevant here; the character with value 0 is NUL.

Gah. Hit send to soon. Also, as much as I'd prefer to avoid
relitigating the absolutely stupid debate about how to expand the
buffers, this is no good:

+ tss->buflen1 = Max(len1 + 1, tss->buflen1 * 2);

If the first expansion is for a string >512MB and the second string is
longer than the first, this will exceed MaxAllocSize and error out.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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