Mastering PostgreSQL 11 - Second Edition

How does ora_migrator work?

The question that now naturally arises is: how does ora_migrator really work? Let's take a look. The first thing ora_migrator does is connect to the Oracle system catalog and copy data into a staging schema on the PostgreSQL side. This is the key to success because we don't have to parse all of the Oracle SQL and try and convert it. By accessing the system tables directly, we can compile the PostgreSQL side on our own, which is a lot easier and a lot more robust. The oracle_fdw extension has all of the mechanisms to do that, and we can therefore easily build on top of it.

Then, the Oracle stuff is cloned into a PostgreSQL staging schema. The idea here is that you might want to change the layout of a table and the ...