Using PostgreSQL through a DB Link connection

Question

Hi,
I'm trying to connect to PostgreSQL using a DB Link connection but when retrieving the users in the Discoverer Administrator after selecting the Database Link I got the following error: Database Error - ORA - 00904: "USERNAME" invalid identifier. It seems that Discoverer is not able to execute a correct Data Dictionary query against PostgreSQL so the users (in this case) are not correctly listed. Is there any configuration option in Oracle Discoverer or DB Link parameter that I can use in order to make it work? What would be your recommendation in this case? Are PostgreSQL and Oracle Discoverer compatible?
Thank you very much

Answer 1

Hi,
I would always recommend that you use database views in situations like this. Then the metadata is held in the Oracle database and you will have no issues importing these views into Discoverer.
So create a schema in your database and in this schema create a view for each PostgreSQL table you want to use, for example, CREATE VIEW myview as SELECT * FROM pgtable@dblink. You can use a script to bulk create the views.
If you want, You can set up primary key and foreign key constraints on these views so that the joins are automatically created when the views are imported into Discoverer. Also the security is much better with views as you only need a private db link and then grant selects on your views to other database users.
Rod West