On Feb 8, 2009, at 9:24 PM, Chris Anderson wrote:
On Sun, Feb 8, 2009 at 5:54 PM, Damien Katz <dam...@apache.org> wrote:
It's possible to use MVCC for replication. You'll need to create
special
HTTP command to return you all the documents you are interested in
a single
request, and a special replicator that uses that command and loads
those
documents and writes them to the destination.
This sound a lot like the notification view Damien's been talking
about, where clients can register to be told about database updates
that match particular functions.
The main problem I see with MVCC replication is that if it dies in the
middle, you might not be able to restart it right where you left off.
That would be a big problem of replicating huge databases. Everything
must come over in one transaction.
If you want consistency on the target, you'll have to write lock the
database (not a concept couchdb really has) until the whole
replication completes, or write all the docs in one big bulk
transaction, which won't work for large databases. And while that
transaction is occurring, neither the source database or target
database file itself be compacted (the compaction will take place, but
the old file can't be freed until the full transaction completes).
-Damien
--
Chris Anderson
http://jchris.mfdz.com
