Horton

Re: [HACKERS] A design for amcheck heapam verification

x4mmm@yandex-team.ru

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From: Andrey Borodin <x4mmm@yandex-team.ru>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Michael Paquier <michael.paquier@gmail.com>, Thomas Munro <thomas.munro@enterprisedb.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2018-03-23T14:13:09Z
Lists: pgsql-hackers 
Hi!

> 8 февр. 2018 г., в 22:45, Peter Geoghegan <pg@bowt.ie> написал(а):
> 
> On Thu, Feb 8, 2018 at 6:05 AM, Andrey Borodin <x4mmm@yandex-team.ru> wrote:
>> I do not see a reason behind hashing the seed.
> 
> It made some sense when I was XOR'ing it to mix. A uniform
> distribution of bits seemed desirable then, since random() won't use
> the most significant bit -- it generates random numbers in the range
> of 0 to 2^31-1. It does seem unnecessary now.
> 
>> Also, I'd like to reformulate this paragraph. I understand what you want to say, but the sentence is incorrect.
>> + * The Bloom filter behaves non-deterministically when caller passes a random
>> + * seed value.  This ensures that the same false positives will not occur from
>> + * one run to the next, which is useful to some callers.
>> Bloom filter behaves deterministically, but differently. This does not ensures any thing, but probably will give something with hight probability.
> 
> I agree that that's unclear. I should probably cut it down, and say
> something like "caller can pass a random seed to make it unlikely that
> the same false positives will occur from one run to the next".

I've just flipped patch to WoA. But if above issues will be fixed I think that patch is ready for committer.

Best regards, Andrey Borodin.

Commits

  1. Fix non-portable use of round().

  2. Add amcheck verification of heap relations belonging to btree indexes.

  3. Add Bloom filter implementation.

  4. Use ereport not elog for some corrupt-HOT-chain reports.

  5. Introduce 64-bit hash functions with a 64-bit seed.

  6. Upgrade src/port/rint.c to be POSIX-compliant.

  7. Use type "int64" for memory accounting in tuplesort.c/tuplestore.c.