Re: replicating DROP commands across servers

Here's a patch implementing the proposed idea. This is used in the
Bidirectional Replication stuff by Simon/Andres; it works well.

One thing of note is that I added output flags for "normal" and
"original", which mostly come from performDeletion flags. This let one
select only such objects when trying to replicate a drop; otherwise,
we'd add RI triggers to the set to drop remotely, which doesn't work
because their names have OIDs embedded, and in the remote system those
are different.

One curious thing is that I had to add a hack that if an object has a
"reverse" flag in the ObjectAddresses array, also set the "normal"
output flag. (Another possibility would have been to add a "reverse"
output flag, but there doesn't seem to be a use for that --- it seems to
expose internals unnecessarily.)

--
Álvaro Herrera http://www.2ndQuadrant.com/
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