The aim of the replication is that at the end of the process, all active documents on the source database are also in the destination database and all documents that were deleted in the source databases are also deleted (if they exist) on the destination database.
Replication can be described as either push or pull replication:
Pull replication is where the
source is the remote CouchDB instance,
and the destination is the local
database.
Pull replication is the most useful solution to use if your source database has a permanent IP address, and your destination (local) database may have a dynamically assigned IP address (for example, through DHCP). This is particularly important if you are replicating to a mobile or other device from a central server.
Push replication is where the
source is a local database, and
destination is a remote database.