Re: Allow GiST opcalsses without compress\decompres functions

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>
Cc: Andrey Borodin <x4mmm(at)yandex-team(dot)ru>, Dmitriy Sarafannikov <dsarafannikov(at)yandex(dot)ru>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Allow GiST opcalsses without compress\decompres functions
Date: 2017-09-20 14:02:35
Message-ID: 6115.1505916155@sss.pgh.pa.us
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Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> writes:
> On Wed, Sep 20, 2017 at 4:25 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Yes. We don't allow out-of-line values, but we do allow compressed and
>> short-header values.

> BTW, this comment looks still invalid for me...

>> #define SIGLENINT 4 /* >122 => key will *toast*, so very slow!!! */

I haven't done the math to see if 122 is exactly the right value,
but at some point index_form_tuple would decide that the tuple was
uncomfortably big and try to compress it. So the comment is right
in general terms.

regards, tom lane

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