Migrating from Oracle to PostgreSQL involves several steps, including exporting the data from Oracle, converting the data to a format that is compatible with PostgreSQL, and then importing the data into PostgreSQL. Here is an overview of the process:

1. Export the data from Oracle: Use the expdp utility to export the data from your Oracle database. This will create a dump file that contains the data in a format that can be imported into PostgreSQL.

2. Convert the data to a format compatible with PostgreSQL: The dump file generated by expdp may contain Oracle-specific syntax that is not compatible with PostgreSQL. Use a tool such as orafce to convert the data to a format that is compatible with PostgreSQL.

3. Import the data into PostgreSQL: Use the psql utility to import the data into your PostgreSQL database.

Note that this is just a high-level overview of the process. Many details and considerations are involved in migrating from Oracle to PostgreSQL, so it’s essential to carefully plan and test the migration before executing it.