# Known limitations for Oracle schema objects

The following limitations apply when Tonic Structural creates the destination database:

* For Oracle advanced queues:
  * Structural does not copy messages from the source database to the destination database.
  * Structural does not copy queue subscribers to the destination database. You must add them to the destination database manually.
* In the destination database, Structural creates external tables as relational tables.
* Structural does not create database links in the destination database. You must create any required database links manually.

Structural also does not support nested tables.