Re: replicating DROP commands across servers

Heikki Linnakangas wrote:
> On 10/03/2014 09:06 PM, Alvaro Herrera wrote:

> >Well, the return value from get_object_address is an ObjectAddress.
> >It's simple enough to create an SQL wrapper that takes the
> >address_names/address_args arrays and return an ObjectAddress; would
> >this be useful?
>
> An ObjectAddress consists of a classid, objid, and objsubid.
> pg_event_trigger_dropped_objects already returns all of those as
> separate fields. What am I missing?

Precisely the point is not returning those values, because they are
useless to identify the equivalent object in a remote database. What we
need is the object names and other stuff used to uniquely identify it
"by user-visible name". We transmit those name arrays to a remote
server, then on the remote server we can run get_object_address and get
the ObjectAddress, which has the classid,objid,objsubid values you cite ...
but for the remote server. The object can then be dropped there.

Initially we thought that we would use the object_identity object for
this (which is why we invented that functionality and added the column
in 9.3), but this turned out not to work very well for unusual object
types; hence this patch.

--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services