Horton

Re: Yet another fast GiST build

Heikki Linnakangas <hlinnaka@iki.fi>

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From: Heikki Linnakangas <hlinnaka@iki.fi>
To: Andrey Borodin <x4mmm@yandex-team.ru>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Justin Pryzby <pryzby@telsasoft.com>, Darafei Komяpa Praliaskouski <me@komzpa.net>, Pavel Borisov <pashkin.elfe@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, Michael Paquier <michael@paquier.xyz>, Alexander Korotkov <a.korotkov@postgrespro.ru>, pgsql-hackers@postgresql.org
Date: 2020-11-02T14:45:56Z
Lists: pgsql-hackers 
On 30/10/2020 20:20, Andrey Borodin wrote:
>> 27 окт. 2020 г., в 16:43, Heikki Linnakangas <hlinnaka@iki.fi> написал(а):
>>> static bool
>>> gbt_inet_abbrev_abort(int memtupcount, SortSupport ssup)
>>> {
>>> #if SIZEOF_DATUM == 8
>>> 	return false;
>>> #else
>>> 	return true;
>>> #endif
>>> }
>>
>> Better to not set the 'abbrev_converter' function in the first place. Or would it be better to cast the float8 to float4 if SIZEOF_DATUM == 4?
> Ok, now for 4 bytes Datum we do return (Datum) Float4GetDatum((float) z);

A few quick comments:

* Currently with float8, you immediately abort abbreviation if 
SIZEOF_DATUM == 4. Like in the 'inet' above, you could convert the 
float8 to float4 instead.

* Some of the ALTER OPERATOR FAMILY commands in btree_gist--1.6--1.7.sql 
are copy-pasted wrong. Here's one example:

ALTER OPERATOR FAMILY gist_timestamptz_ops USING gist ADD
	FUNCTION	11	(text, text) gbt_text_sortsupport;

* It's easy to confuse the new comparison functions with the existing 
comparisons used by the picksplit functions. Some comments and/or naming 
changes would be good to clarify how they're different.

* It would be straightforward to have abbreviated functions for macaddr 
and macaddr8 too.

> How do you think, should this patch and patch with pageinspect GiST functions be registered on commitfest?

Yeah, that'd be good.

- Heikki

Commits

  1. Add sortsupport for gist_btree opclasses, for faster index builds.

  2. pageinspect: Fix relcache leak in gist_page_items().

  3. Fix test failure with wal_level=minimal.

  4. Enhance nbtree index tuple deletion.

  5. Fix portability issues in the new gist pageinspect test.

  6. Add functions to 'pageinspect' to inspect GiST indexes.

  7. Fix missing validation for the new GiST sortsupport functions.

  8. Fix compilation warning in xlog.c

  9. Set right-links during sorted GiST index build.

  10. Fix checksum calculation in the new sorting GiST build.

  11. Add support for building GiST index by sorting.