AW: AW: Postgres Replication

> Here are some disadvantages to using a "trigger based" approach:
> 
> 1) Triggers simply transfer individual data items when they 
> are modified, they do not keep track of transactions.
> 2) The execution of triggers within a database imposes a performance 
> overhead to that database.
> 3) Triggers require careful management by database administrators.  
> Someone needs to keep track of all the "alarms" going off.
> 4) The activation of triggers in a database cannot be easily 
> rolled back or undone.

Yes, points 2 and 3 are a given, although point 2 buys you the functionality
of transparent locking across all involved db servers.
Points 1 and 4 are only the case for a trigger mechanism that does 
not use remote connection and 2-phase commit. 

Imho an implementation that opens a separate client connection to the 
replication target is only suited for async replication, and for that a WAL 
based solution would probably impose less overhead.

Andreas