| From: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
|---|---|
| To: | Andrey Borodin <x4mmm(at)yandex-team(dot)ru> |
| Cc: | Peter Geoghegan <pg(at)bowt(dot)ie>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, Darafei Komяpa Praliaskouski <me(at)komzpa(dot)net>, Pavel Borisov <pashkin(dot)elfe(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Ibrar Ahmed <ibrar(dot)ahmad(at)gmail(dot)com> |
| Subject: | Re: Yet another fast GiST build |
| Date: | 2021-04-07 06:00:10 |
| Message-ID: | 6d795a95-bb6b-b993-7c21-64bb7acd3648@iki.fi |
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| Lists: | pgsql-hackers |
On 08/03/2021 19:06, Andrey Borodin wrote:
> There were numerous GiST-build-related patches in this thread. Yet uncommitted is a patch with sortsupport routines for btree_gist contrib module.
> Here's its version which needs review.
Reviewing this now again. One thing caught my eye:
> +static int
> +gbt_bit_sort_build_cmp(Datum a, Datum b, SortSupport ssup)
> +{
> + return DatumGetInt32(DirectFunctionCall2(byteacmp,
> + PointerGetDatum(a),
> + PointerGetDatum(b)));
> +}
That doesn't quite match the sort order used by the comparison
functions, gbt_bitlt and such. The comparison functions compare the bits
first, and use the length as a tie-breaker. Using byteacmp() will
compare the "bit length" first. However, gbt_bitcmp() also uses
byteacmp(), so I'm a bit confused. So, huh?
- Heikki
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