Re: [HACKERS] A design for amcheck heapam verification
От | Andrey Borodin |
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Тема | Re: [HACKERS] A design for amcheck heapam verification |
Дата | |
Msg-id | A00E5441-D5AA-4C46-A4E7-ECE6EF48179A@yandex-team.ru обсуждение исходный текст |
Ответ на | Re: [HACKERS] A design for amcheck heapam verification (Peter Geoghegan <pg@bowt.ie>) |
Ответы |
Re: [HACKERS] A design for amcheck heapam verification
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Список | 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 somethingwith 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.
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