Horton

Re: new heapcheck contrib module

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mark Dilger <mark.dilger@enterprisedb.com>
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: 2020-10-22T21:06:19Z
Lists: pgsql-hackers 
I wrote:
> Mark Dilger <mark.dilger@enterprisedb.com> writes:
>> It is seeking to position 32 and writing '\x77\x77\x77\x77'.  x86_64 is
>> little-endian, and ppc32 and sparc64 are both big-endian, right?

> They are, but that should not meaningfully affect the results of
> that corruption step.  You zapped only one line pointer not
> several, but it would look the same regardless of endiannness.

Oh, wait a second.  ItemIdData has the flag bits in the middle:

typedef struct ItemIdData
{
    unsigned    lp_off:15,        /* offset to tuple (from start of page) */
                lp_flags:2,       /* state of line pointer, see below */
                lp_len:15;        /* byte length of tuple */
} ItemIdData;

meaning that for that particular bit pattern, one endianness
is going to see the flags as 01 (LP_NORMAL) and the other as 10
(LP_REDIRECT).  The offset/len are corrupt either way, but
I'd certainly expect that amcheck would produce different
complaints about those two cases.  So it's unsurprising if
this test case's output is endian-dependent.

			regards, tom lane

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.