Horton

Re: new heapcheck contrib module

Mark Dilger <mark.dilger@enterprisedb.com>

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From: Mark Dilger <mark.dilger@enterprisedb.com>
To: "Andrey M. Borodin" <x4mmm@yandex-team.ru>
Cc: Robert Haas <robertmhaas@gmail.com>, Amul Sul <sulamul@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Peter Geoghegan <pg@bowt.ie>, Andres Freund <andres@anarazel.de>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2020-08-28T18:23:56Z
Lists: pgsql-hackers 

> On Aug 28, 2020, at 11:10 AM, Andrey M. Borodin <x4mmm@yandex-team.ru> wrote:
> 
> 
> 
>> 28 авг. 2020 г., в 18:58, Robert Haas <robertmhaas@gmail.com> написал(а):
>> In the case
>> you mention, I think we should view that as a problem with clog rather
>> than a problem with the table, and thus out of scope.
> 
> I don't think so. ISTM It's the same problem of xmax<relfrozenxid actually, just hidden behind detoasing.
> Our regular heap_check was checking xmin\xmax invariants for tables, but failed to recognise the problem in toast (while toast was accessible until CLOG truncation).
> 
> Best regards, Andrey Borodin.

If you lock the relations involved, check the toast table first, the toast index second, and the main table third, do you still get the problem?  Look at how pg_amcheck handles this and let me know if you still see a problem.  There is the ever present problem that external forces, like a rogue process deleting backend files, will strike at precisely the wrong moment, but barring that kind of concurrent corruption, I think the toast table being checked prior to the main table being checked solves some of the issues you are worried about.

—
Mark Dilger
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Add pg_amcheck, a CLI for contrib/amcheck.

  2. Refactor and generalize the ParallelSlot machinery.

  3. Generalize parallel slot result handling.

  4. Move some code from src/bin/scripts to src/fe_utils to permit reuse.

  5. Factor pattern-construction logic out of processSQLNamePattern.

  6. Doc: clean up verify_heapam() documentation.

  7. Fix more portability issues in new amcheck code.

  8. Fix portability issues in new amcheck test.

  9. Try to avoid a compiler warning about using fxid uninitialized.

  10. Extend amcheck to check heap pages.

  11. Adjust walsender usage of xlogreader, simplify APIs

  12. Improve checking of child pages in contrib/amcheck.

  13. Sanitize line pointers within contrib/amcheck.

  14. Fix possible sorting error when aborting use of abbreviated keys.