Re: [jira] Commented: (DERBY-239) Need a online backup feature that does not block update operations when online backup is in progress.

[Mike Matrigali <mi...@sbcglobal.net>]

In general I also don't like implicit commits either.

I think there
is really only 2 options - possibly throw an error if the backup
is started by a thread with an outstanding unlogged operation or not.  I 
think the set lock mode command is
the only current one in Derby to do implicit commits, and I believe that 
is part of the standard.

I don't think the nested transaction helps here as the problem is that
backup needs to wait for transactions with unlogged operations to 
complete, which in the
case suresh is discussing the unlogged operation was performed by the
same thread doing the backup.

Just starting a nested transaction doesn't help, as the unlogged
operation is still out there, and will wait forever on itself.

Øystein Grøvlen wrote:
>>>>>>"MM" == Mike Matrigali <mi...@sbcglobal.net> writes:
> 
> 
>     MM> I like option 1, make sure it is well documented.  I actually lean
>     MM> toward even stronger, have the command commit the current transaction
>     MM> before and after the backup.
> 
> Generally, I do not like such implicit commits.  It is likely to catch
> someone by surprise.  On the other, I do not think many people would
> intentionally do backup as part of a larger transaction.
> 
> In my opinion, the ideal solution would be to execute backup in a
> nested transaction.  I do not know whether it is worth the effort.
>