Horton

Re: new heapcheck contrib module

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Mark Dilger <mark.dilger@enterprisedb.com>, Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2020-05-13T22:10:51Z
Lists: pgsql-hackers 
On 2020-May-12, Peter Geoghegan wrote:

> > The point is that when checking the table for corruption I avoid
> > calling anything that might assert (or segfault, or whatever).
> 
> I don't think that you can expect to avoid assertion failures in
> general.

Hmm.  I think we should (try to?) write code that avoids all crashes
with production builds, but not extend that to assertion failures.
Sticking again with the provided example,

> I'll stick with your example. You're calling
> TransactionIdDidCommit() from check_tuphdr_xids(), which will
> interrogate the commit log and pg_subtrans. It's just not under your
> control.

in a production build this would just fail with an error that the
pg_xact file cannot be found, which is fine -- if this happens in a
production system, you're not disturbing any other sessions.  Or maybe
the file is there and the byte can be read, in which case you would get
the correct response; but that's fine too.

I don't know to what extent this is possible.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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.