Re: Block-level CRC checks
От | pgsql@mohawksoft.com |
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Тема | Re: Block-level CRC checks |
Дата | |
Msg-id | 47015.71.232.149.185.1222809205.squirrel@mail.mohawksoft.com обсуждение исходный текст |
Ответ на | Re: Block-level CRC checks (Decibel! <decibel@decibel.org>) |
Ответы |
Re: Block-level CRC checks
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Список | pgsql-hackers |
> > I believe the idea was to make this as non-invasive as possible. And > it would be really nice if this could be enabled without a dump/ > reload (maybe the upgrade stuff would make this possible?) > -- It's all about the probability of a duplicate check being generated. If you use a 32 bit checksum, then you have a theoretical probability of 1 in 4 billion that a corrupt block will be missed (probably much lower depending on your algorithm). If you use a short, then a 1 in 65 thousand probability. If you use an 8 bit number, then 1 in 256. Why am I going on? Well, if there are any spare bits in a block header, they could be used for the check value.
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