Horton

Re: new heapcheck contrib module

Mark Dilger <mark.dilger@enterprisedb.com>

View thread View on postgr.es
From: Mark Dilger <mark.dilger@enterprisedb.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Peter Geoghegan <pg@bowt.ie>, "Andrey M. Borodin" <x4mmm@yandex-team.ru>, Stephen Frost <sfrost@snowman.net>, Michael Paquier <michael@paquier.xyz>, Amul Sul <sulamul@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Andres Freund <andres@anarazel.de>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2020-10-23T01:59:03Z
Lists: pgsql-hackers 

> On Oct 22, 2020, at 6:50 PM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:
> 
> 
> 
>> On Oct 22, 2020, at 6:46 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> 
>> I wrote:
>>> I get
>>> off = 7777, flags = 2, len = 3bbb
>>> on a little-endian machine, and
>>> off = 3bbb, flags = 2, len = 7777
>>> on big-endian.  It'd be less symmetric if the bytes weren't
>>> all the same ...
>> 
>> ... but given that this is the test value we are using, why
>> don't both endiannesses whine about a non-maxalign'd offset?
>> The code really shouldn't even be trying to follow these
>> redirects, because we risk SIGBUS on picky architectures.
> 
> Ahh, crud.  It's because
> 
> 	syswrite($fh, '\x77\x77\x77\x77', 500)
> 
> is wrong twice.  The 500 was wrong, but the string there isn't the bit pattern we want -- it's just a string literal with backslashes and such.  It should have been double-quoted.

The reason this never came up in testing is what I was talking about elsewhere -- this test isn't designed to create *specific* corruptions.  It's just supposed to corrupt the table in some random way.  For whatever reasons I'm not too curious about, that string corrupts on little endian machines but not big endian machines.  If we want to have a test that tailors very specific corruptions, I don't think the way to get there is by debugging this test.

—
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.