Horton

Re: Yet another fast GiST build

Heikki Linnakangas <hlinnaka@iki.fi>

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From: Heikki Linnakangas <hlinnaka@iki.fi>
To: "Andrey M. 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: 2020-09-21T12:15:18Z
Lists: pgsql-hackers 
On 21/09/2020 12:06, Andrey M. Borodin wrote:
>> 21 сент. 2020 г., в 13:45, Heikki Linnakangas <hlinnaka@iki.fi>
>> написал(а):
>> 
>> Actually, don't we have a problem with that, even before this
>> patch? Even though we set the LSN to the magic GistBuildLSN value
>> when we build the index, WAL replay will write the LSN of the
>> record instead. That would mess with the LSN-NSN interlock. After
>> WAL replay (or in a streaming replica), a scan on the GiST index
>> might traverse right-links unnecessarily.
> 
> I think we don't set rightlinks during index build.

The new GiST sorting code does not, but the regular insert-based code does.

That's a bit questionable in the new code actually. Was that a conscious
decision? The right-links are only needed when there are concurrent page
splits, so I think it's OK, but the checks for InvalidBlockNumber in
gistScanPage() and gistFindPage() have comment "/* sanity check */".
Comment changes are needed, at least.

- 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.