Horton
Menu

Re: Amcheck verification of GiST and GIN

Kirill Reshke <reshkekirill@gmail.com>

View thread
From: Kirill Reshke <reshkekirill@gmail.com>
To: Mark Dilger <mark.dilger@enterprisedb.com>
Cc: Tomas Vondra <tomas@vondra.me>, "Andrey M. Borodin" <x4mmm@yandex-team.ru>, Alexander Lakhin <exclusion@gmail.com>, Andrey Borodin <amborodin86@gmail.com>, Peter Geoghegan <pg@bowt.ie>, Jose Arthur Benetasso Villanova <jose.arthur@gmail.com>, Andres Freund <andres@anarazel.de>, Nikolay Samokhvalov <samokhvalov@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-03-01T14:55:31Z
Lists: pgsql-hackers

Attachments

On Fri, 28 Feb 2025 at 23:31, Mark Dilger <mark.dilger@enterprisedb.com> wrote:

> The only obvious definition of "wrong" for this is that gin index scans return different result sets than table scans over the same data.  Using your much smaller reproducible test case, and adding rows like:

Yeach, you are 100% right. Actually, along this thread, we have not
spotted any GIN bugs yet, only GIN amcheck bugs.

This turns out to be also an GIN amcheck bug:

```
DEBUG:  comparing for offset 79  category 2  key attnum 1
DEBUG:  comparing for offset 80  category 3  key attnum 1
DEBUG:  comparing for offset 81  category 0  key attnum 2
LOG:  index "ginidx" has wrong tuple order on entry tree page, block
2, offset 81, rightlink 4294967295
DEBUG:  comparing for offset 82  category 0  key attnum 2
....
DEBUG:  comparing for offset 100  category 0  key attnum 2
DEBUG:  comparing for offset 101  category 2  key attnum 2
DEBUG:  comparing for offset 102  category 3  key attnum 2
DEBUG:  comparing for offset 103  category 0  key attnum 3
LOG:  index "ginidx" has wrong tuple order on entry tree page, block
2, offset 103, rightlink 4294967295
DEBUG:  comparing for offset 104  category 0  key attnum 3
DEBUG:  comparing for offset 105  category 0  key attnum 3
```
Turns out we compare page entries for different attributes in
gin_check_parent_keys_consistency.

Trivial fix attached (see v37-0004). I now simply compare current and
prev attribute numbers. This revolves issue discovered by
`v0-0001-Add-a-reproducible-test-case-for-verify_gin-error.patch.no_apply`.
However, the stress test seems to still not pass. On my pc, it never
ens, all processes are in
DELETE waiting/UPDATE waiting state. I will take another look tomorrow.



p.s. I am just about to send this message, while i discovered we now
miss v34-0003-Add-gist_index_check-function-to-verify-GiST-ind.patch &
v34-0005-Add-GiST-support-to-pg_amcheck.patch from this patch series
;(

-- 
Best regards,
Kirill Reshke

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. amcheck: Fix posting tree checks in gin_index_check()

  2. amcheck: Fix parent key check in gin_index_check()

  3. amcheck: Fix checks of entry order for GIN indexes

  4. amcheck: Remove unused GinScanItem->parentlsn field

  5. amcheck: Test gin_index_check on a multicolumn index

  6. Remove incidental md5() function use from test

  7. amcheck: Add a GIN index to the CREATE INDEX CONCURRENTLY tests

  8. amcheck: Add a test with GIN index on JSONB data

  9. amcheck: Fix indentation in verify_gin.c

  10. amcheck: Add gin_index_check() to verify GIN index

  11. amcheck: Move common routines into a separate module

  12. Fix grammar in GIN README

  13. Avoid amcheck inline compression false positives.