HMS Metadata migration from Postgres/Derby to other DBs fail

Customer recently was migrating from Postgres to Oracle for HMS metastore. During import of the [exported] data from HMS metastore from postgres, failures are seen as the COLUMNS_V2.COMMENT is 4000 bytes long whereas oracle and other schemas define it to be 256 bytes.
This inconsistency in the schema makes the migration cumbersome and manual. This jira makes this column consistent in length across all databases.