Better dual WAL shipping/streaming integration?

Hi.

I currently have a number of servers using both streaming replication
and WAL shipping in the standard setup.

Occasionally, the primaries get large load spikes. Load climbs up,
things slow down. So much so that streaming replication starts lagging
because the WAL sender is being starved for resources. Eventually, the
slave disconnects. At which point it happily starts consuming the
shipped files and catches up again.

All this is working just fine and as designed (apart from the load
spikes, but that is my problem). However, I was thinking that it would
be better streaming replication did not attempt to pull down WAL files
that had already been shipped and were available locally. This would
save resources when you need them most - the hot standbys have fallen
behind.

--
Stuart Bishop <stuart(at)stuartbishop(dot)net>
http://www.stuartbishop.net/