Tuesday, July 15, 2008

Re: [ADMIN] Backup and failover process

>>> "Campbell, Lance" <lance@illinois.edu> wrote:

> What happens if you take an SQL snapshot of a database while
> creating WAL archives then later restore from that SQL snapshot and
> apply those WAL files?

What do you mean by "an SQL snapshot of a database"? WAL files only
come into play for backup techniques which involve file copies, not
dumps done using SQL commands (like pg_dump).

> Will there be a problem if the transactions
> within the newest WAL file after the SQL snapshot was taken cause
> problems when they are applied?

Point In Time Recovery (PITR) backup techniques allow you to restore
to a specified point in time, so you could restore up to the point
immediately before the problem transactions.

> I would assume yes but I wanted to
> check if there was some type of timestamp that would prevent an
issue
> from occurring?

Take another look at this section -- in particular,
recovery_target_time.

I hope this helps.

-Kevin

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