On Sat, Mar 31, 2012 at 6:58 PM, Andreas <maps...@gmx.net> wrote: > > > Now what could one do to prevent those sequence gaps? > There might be scenarios where it's important not to have gaps in the > numbering even when one has to switch to the standby if there is a failiour > on the master. > E.g. numbers of invoices need to be gapless. > > Then you may need to find some other way within your application to assign invoice numbers, because sequences aren't GUARANTEED not to have gaps, especially if there is a failure of the primary server that results in a switch over to the standby server.
A transaction that is rolled back (such as due to an error) after the nextval() function has been called will not roll back the sequence value, for example. You cannot issue a nextval() call on a standby server, because it is in read-only mode. -- MIke Nolan
