Horton

Re: Yet another fast GiST build

x4mmm@yandex-team.ru

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From: "Andrey M. Borodin" <x4mmm@yandex-team.ru>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Pavel Borisov <pashkin.elfe@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, Michael Paquier <michael@paquier.xyz>, Alexander Korotkov <a.korotkov@postgrespro.ru>, Darafei Komяpa Praliaskouski <me@komzpa.net>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2020-09-09T06:43:40Z
Lists: pgsql-hackers 

> 9 сент. 2020 г., в 00:05, Heikki Linnakangas <hlinnaka@iki.fi> написал(а):
> 
> I've been reviewing the patch today. The biggest changes I've made have been in restructuring the code in gistbuild.c for readability, but there are a bunch of smaller changes throughout. Attached is what I've got so far, squashed into one patch.
Thanks!

> I'm continuing to review it, but a couple of questions so far:
> 
> In the gistBuildCallback(), you're skipping the tuple if 'tupleIsAlive == false'. That seems fishy, surely we need to index recently-dead tuples, too. The normal index build path isn't skipping them either.
That's an oversight.
> 
> How does the 'sortsupport' routine interact with 'compress'/'decompress'? Which representation is passed to the comparator routine: the original value from the table, the compressed representation, or the decompressed representation? Do the comparetup_index_btree() and readtup_index() routines agree with that?

Currently we pass compressed values, which seems not very good.
But there was a request from PostGIS maintainers to pass values before decompression.
Darafei, please, correct me if I'm wrong. Also can you please provide link on PostGIS B-tree sorting functions?

Thanks!

Best regards, Andrey Borodin.

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.