Re: 16-bit page checksums for 9.2
| От | Simon Riggs |
|---|---|
| Тема | Re: 16-bit page checksums for 9.2 |
| Дата | |
| Msg-id | CA+U5nMJK89jFTKCmegnoKRShaSTamFs4RLr6Fyshu1R05htq4g@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: 16-bit page checksums for 9.2 (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>) |
| Ответы |
Re: 16-bit page checksums for 9.2
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| Список | pgsql-hackers |
On Tue, Dec 27, 2011 at 8:05 PM, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> wrote: > On 25.12.2011 15:01, Kevin Grittner wrote: >> >> I don't believe that. Double-writing is a technique to avoid torn >> pages, but it requires a checksum to work. This chicken-and-egg >> problem requires the checksum to be implemented first. > > > I don't think double-writes require checksums on the data pages themselves, > just on the copies in the double-write buffers. In the double-write buffer, > you'll need some extra information per-page anyway, like a relfilenode and > block number that indicates which page it is in the buffer. How would you know when to look in the double write buffer? -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
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