In version 11 and earlier, PostgreSQL doesn’t provide a feature that is directly equivalent to an Oracle virtual column. Handling virtual generated columns while migrating from Oracle Database to PostgreSQL version 11 or earlier is difficult for two reasons:
Virtual columns aren’t visible during migration.
PostgreSQL doesn't support the generate expression before version 12.
However, there are workarounds to emulate similar functionality. When you use AWS Database Migration Service (AWS DMS) to migrate data from Oracle Database to PostgreSQL version 11 and earlier, you can use trigger functions to populate the values in virtual generated columns. This pattern provides examples of Oracle Database and PostgreSQL code that you can use for this purpose. On AWS, you can use Amazon Relational Database Service (Amazon RDS) for PostgreSQL or Amazon Aurora PostgreSQL-Compatible Edition for your PostgreSQL database.
Starting with PostgreSQL version 12, generated columns are supported. Generated columns can either be calculated from other column values on the fly, or calculated and stored. PostgreSQL generated columns are similar to Oracle virtual columns.
