Chris Travers wrote:
I guess I am thinking along different lines than you. I was thinking
that the simplest solution would be to have master/slave replication for
*approved* transactions only and no replication for initial commits
prior to approval. This makes the assumption that a single transaction
will be committed on a single server, and that a single transaction will
not be split over multiple servers. In this way, you can commit a
pending transaction to any single server, and when it is approved, it
gets replicated via the master. See below for more.
This works if you don't care that multiple servers commit transactions
that force a budget or bank account to be exceeded.
Thinking about this.... The big issue is that you only want to
replicate the deltas, not the entire account. I am still thinking
master/slave, but something where the deltas are replicated in the
background or where the user, in checking his account, is actually
querying the home server. This second issue could be done via dblink or
DBI-Link and would simply require that a master table linking the
accounts with home servers be replicated (this should, I think, be
fairly low-overhead).
Except what you know have is your system fails if any server fail or is
inaccessible.
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