Aw: Re: pg_dump include/exclude data, was: verify checksums /CREATE DATABASE
От | Karsten Hilbert |
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Тема | Aw: Re: pg_dump include/exclude data, was: verify checksums /CREATE DATABASE |
Дата | |
Msg-id | trinity-09990bfd-ae66-4c01-b9bb-cafb31a57e9f-1560276934383@3c-app-gmx-bs19 обсуждение исходный текст |
Ответ на | Re: pg_dump include/exclude data, was: verify checksums / CREATEDATABASE (Adrian Klaver <adrian.klaver@aklaver.com>) |
Ответы |
Re: Aw: Re: pg_dump include/exclude data, was: verify checksums /CREATE DATABASE
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Список | pgsql-general |
> > The problem I hope to protect against with this approach: the > > CREATE DATABASE might untaint corrupted data from a bad disk > > block into a good disk block virtue of doing a file level > > copy. > > > > I hope my reasoning isn't going astray. > > As I understand it checksums are done on the page level using a hash(for > details: https://doxygen.postgresql.org/checksum__impl_8h_source.html). > I am not sure how a page could get un-corrupted by virtue of a file copy. Ah, no, I did not explain myself well. Let's assume a corrupted, bad (but readable at the hardware level) disk block B. A filesystem level copy (as in CREATE DATABASE) would successfully read that disk block B and copy the corrupted content into a good disk block G elsewhere on the disk. Verifying the checksum of the page sitting on block B before doing the database cloning would reveal the corruption before it got cloned. Does that make sense ? Karsten
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