Horton

Re: GiST VACUUM

x4mmm@yandex-team.ru

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From: Andrey Borodin <x4mmm@yandex-team.ru>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Robert Haas <robertmhaas@gmail.com>, Thomas Munro <thomas.munro@enterprisedb.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Костя Кузнецов <chapaev28@ya.ru>
Date: 2018-07-21T12:11:34Z
Lists: pgsql-hackers

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Hi!

> 19 июля 2018 г., в 23:26, Andrey Borodin <x4mmm@yandex-team.ru> написал(а):
> 
> I'm working on triggering left split during vacuum. Will get back when done. Thanks!

Here's patch including some messy hacks to trigger NSN and FollowRight jumps during VACUUM.

To trigger FollowRight GiST sometimes forget to clear follow-right marker simulating crash of an insert. This fills logs with "fixing incomplete split" messages. Search for "REMOVE THIS" to disable these ill-behavior triggers.
To trigger NSN jump GiST allocate empty page after every real allocation.

gistvacuumcleanup() was constantly generating left jumps because there was used 0 instead of real start NSN, I moved NSN acquisition to gistvacuumscan(). Also fixed some comments.

gistvacuumcleanup() will have same effect as gistbulkdelete(), is it OK?

To reproduce left-jumps run ./rescantest.sh
Script contain variables for my local paths.


Best regards, Andrey Borodin.

Commits

  1. Use full 64-bit XID for checking if a deleted GiST page is old enough.

  2. Refactor checks for deleted GiST pages.

  3. Delete empty pages during GiST VACUUM.

  4. Scan GiST indexes in physical order during VACUUM.

  5. Prevent GIN deleted pages from being reclaimed too early