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: 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: 2020-09-21T13:29:14Z
Lists: pgsql-hackers 

> 21 сент. 2020 г., в 17:15, Heikki Linnakangas <hlinnaka@iki.fi> написал(а):
> 
> On 21/09/2020 12:06, Andrey M. Borodin wrote
>> 
>> 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.

It was a conscious decision with incorrect motivation. I was thinking that it will help to reduce number of "false positive" inspecting right pages. But now I see that:
1. There should be no such "false positives" that we can avoid
2. Valid rightlinks could help to do amcheck verification in future

But thing that bothers me now: when we vacuum leaf page, we bump it's NSN. But we do not bump internal page LSN. Does this means we will follow rightlinks after vacuum? It seems superflous. And btw we did not adjust internal page tuples after vacuum...

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.