Ora2Pg is a free tool used to migrate an Oracle database to a PostgreSQL compatible schema. It connects your
Oracle database, scan it automaticaly and extracts its structure or data, it then generates SQL scripts that you can
load into your PostgreSQL database.
Ora2Pg can be used from reverse engineering Oracle database to huge enterprise database migration or simply to replicate
some Oracle data into a PostgreSQL database. It is really easy to used and doesn't need any Oracle database knowledge than
providing the parameters needed to connect to the Oracle database.
Slony-I is a "master to multiple slaves" replication system supporting cascading (e.g. - a node can feed another node which feeds another node...) and failover.