I want to keep oracle and orientdb databases in near real time sync and vice versa. Is there any tool/ mechanism to follow.
OrientDB had just released a new tool that allows exactly what you want. Its name is Teleporter and you can use it to:
This tool supports migration and sync with Oracle, SQLServer, MySQL, PostgreSQL and HSQLDB DBMSs.
Teleported has been released few days ago with the new orientdb 2.2.0-beta version and even though is not yet integrated (it isn't a definitive release) is really easy to insall. Here is the Teleporter page on orientdb.com:
http://orientdb.com/orientdb-labs/teleporter/
and here you can find the link to the documentation:
https://github.com/orientechnologies/orientdb-labs/blob/master/Teleporter-Index.md