warm standby and reciprocating failover.

Hello,

I have a working warm standby system, running 8.4 (thanks for urging
me to upgrade from the rehdat provided release).
One of the new requirements is going to be for (a non-DBA) admin to
easily swap services between the two servers for maintenance.

The first move runs easily as expected- postgres ships the last
partial wal immediately on shutdown, trigger the standby and we're up.
I'm now running into issues bringing the first server back up in
standby mode. After the second server finishes recovery, the major
number of the wal files is incremented (say from 00000001 to
00000002), and the 00000002.history file is shipped back to the first
server. The first server however is still looking for 00000001x files.

Is there a way to ship back the missing information from the recovery
process, without doing another base backup of data/ ?

Thanks
-jim