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: 2020-10-23T01:41:15Z
Lists: pgsql-hackers 
I wrote:
> So now I think this is a REDIRECT on either architecture, but the
> offset and length fields have different values, causing the redirect
> pointer to point to different places.  Maybe it happens to point
> at a DEAD tuple in the big-endian case.

Just to make sure, I tried this test program:

#include <stdio.h>
#include <string.h>

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;

int main()
{
    ItemIdData lp;

    memset(&lp, 0x77, sizeof(lp));
    printf("off = %x, flags = %x, len = %x\n",
           lp.lp_off, lp.lp_flags, lp.lp_len);
    return 0;
}

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 ...

			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.