Re: [GENERAL] requested timeline doesn't contain minimum recovery point

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От Tom DalPozzo
Тема Re: [GENERAL] requested timeline doesn't contain minimum recovery point
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Msg-id CAK77FCRC074zbDQMCMA2=GE_WRzP0RyjymrfDEYPrGFbhPHaeQ@mail.gmail.com
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Ответ на Re: [GENERAL] requested timeline doesn't contain minimum recovery point  (Michael Paquier <michael.paquier@gmail.com>)
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> I mean, could random bytes appear as a valid record (very unlikely, but
> possible)?

Yes, that could be possible if some memory or disk is broken. That's
why, while it is important to take backups, it is more important to
make sure that they are able to restore correctly before deploying
them.
--
Michael
Hi,
of course against memory or disk corruption, nothing 100% safe can be done. But, excluding these cases, can there be situations in which the WAL reader gets confused?
I'm thinking at WAL segments recycling: when a WAL is recycled it is not filled with anything (zeroes...) right? 
If I'm right, then there are still old records in the WAL. If they're aligned with the new offsets, I guess that the system can understand that they're older (looking at some ID) and not valid but if not aligned, there could be an unlucky and unlikely issue.

In other word,  excluding HW problems and possible unwanted bugs, I'd like to know if the logic underneath WAL reading at startup is 100%safe.

Regards
Pupillo


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