Horton

Re: Yet another fast GiST build

x4mmm@yandex-team.ru

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From: Andrey Borodin <x4mmm@yandex-team.ru>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Peter Geoghegan <pg@bowt.ie>, 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>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Ibrar Ahmed <ibrar.ahmad@gmail.com>
Date: 2021-04-07T12:12:21Z
Lists: pgsql-hackers 

> 7 апр. 2021 г., в 13:23, Heikki Linnakangas <hlinnaka@iki.fi> написал(а):
> 
> Committed with small fixes.

Thanks!

> 7 апр. 2021 г., в 14:56, Heikki Linnakangas <hlinnaka@iki.fi> написал(а):
> 
> Ok, I think I understand that now. In btree_gist, the *_cmp() function operates on non-leaf values, and *_lt(), *_gt() et al operate on leaf values. For all other datatypes, the leaf and non-leaf representation is the same, but for bit/varbit, the non-leaf representation is different. The leaf representation is VarBit, and non-leaf is just the bits without the 'bit_len' field. That's why it is indeed correct for gbt_bitcmp() to just use byteacmp(), whereas gbt_bitlt() et al compares the 'bit_len' field separately. That's subtle, and 100% uncommented.
> 
> What that means for this patch is that gbt_bit_sort_build_cmp() should *not* call byteacmp(), but bitcmp(). Because it operates on the original datatype stored in the table.

+1
Thanks for investigating this.
If I understand things right, adding test values with different lengths of bit sequences would not uncover the problem anyway?

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.