Re: Replication : database triggers vs log sniffing

voodoo <voodoo_at_netvision.net.il> writes:

>Is there anyone out there who knows why database triggers used in
>oracle's replication are BETTER than log sniffing used in other
>databases? is log sniffing faster ?? unfortunately i have no idea what
>database uses log sniffing . I need this information in order to
>convince a hopefully future user of oracle.

Database triggers are probably easier to write and maintain, and upward compatibility is more assured because you're using Oracle features exclusively. Log sniffing, while useful, is at this point dependent on a 3rd party vendor's ability to figure out what Oracle puts in their logs in future releases. It also assumes that the logs remain intact. (But if they aren't intact, your user has a more serious problem to deal with anyway.)

Triggers are also likely to be more immediate, although they can also be used to archive transactions for future replication or when the remote system is unavailable. This could also be considered a disadvantage, especially on a system with peak load problems. Replication via log sniffing could be performed off-peak or even on other systems.

--
Mike Nolan
nolan_at_tssi.com