Re: Does PostgreSQL check database integrity at startup?

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От rob stone
Тема Re: Does PostgreSQL check database integrity at startup?
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Msg-id 1514326316.3143.16.camel@gmail.com
обсуждение исходный текст
Ответ на Re: Does PostgreSQL check database integrity at startup?  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
Ответы Re: Does PostgreSQL check database integrity at startup?  (Edson Carlos Ericksson Richter <richter@simkorp.com.br>)
Список pgsql-hackers
Hello,


On Tue, 2017-12-26 at 18:58 -0300, Alvaro Herrera wrote:Hello,
> David Steele wrote:
> 
> > pgBackRest will validate all page checksums (including indexes,
> > etc.) in the
> > cluster during backup.  Full backups check everything,
> > incr/differential
> > backups check only the files that have changed.
> 
> If a table or index file is of zero length when backed up, as in the
> described case, nothing will be checked, right?  I mean, there is
> nothing externally indicating that the file ought to be of a
> different
> size.  Am I wrong?  So Edson's situation here would not raise any red
> flags.
> 


Could the following occur:-
1) Your app. issues a BEGIN followed by an INSERT.
2) Postgres decides to open a new file in order to store the new row.
3) Your app. then does a ROLLBACK.

Wouldn't that leave you with a zero length file on disk?

There's no reason for Postgres to delete the file just because a
rollback was issued. All it has to do is clear the buffer in memory.

My 2 cents.

Rob 


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