[Pdns-users] Slight problem with PostgreSQL backend AXFR query

[ktm at rice.edu]

On Fri, Mar 28, 2014 at 09:41:50AM -0400, Stephen Frost wrote:
> Ken,
> 
> * ktm at rice.edu (ktm at rice.edu) wrote:
> > While debugging a new installation we noticed that a slow zone transfer
> > using a PostgreSQL backend would insert duplicate records if the transfer
> > took over 1 minute and a second transfer was started before the first
> > one completed. 
> 
> Shouldn't there be a constraint here to prevent duplicate data from
> getting into the database..?  I agree that the transaction isolation
> level might be an issue also, but duplicate data should be prevented by
> constraints also.
> 
> 	Thanks,
> 
> 		Stephen

Hi Stephen,

According to the code comments, they expect the DB to abort the second
attempt to start a transaction for a zone AXFR, so the isolation level
must be set to provide that assurance. It is fortunate that is looks like
both PostgreSQL and MySQL can both use the same session level isolation
setting syntax.

Regards,
Ken