Too many results for query

Question

Hello,
I'm using Oracle to teach my students database programming with VB.NET (ADO.NET). During my course, I introduce the DataAdapter Configuration wizard of Visual Studio for creating a connection and dataadapter. I'm using OleDb (from Microsoft) to connect to Oracle.
The problem is that this wizard asks Oracle for all the tables that can possibly be used for a user. When 20 students do this exercise at the same time, the Oracle DB (we use release 9, version 2 on Windows) responds extremely slow.
I used tracing to search for the query that this wizard generates (using trace files) and I found this one:
select * from (select null table_catalog, decode (o1.owner, 'PUBLIC', NULL, o1.owner) table_schema, o1.object_name table_name, decode(o1.owner,'SYS',decode(o1.object_type,'TABLE','SYSTEM TABLE','VIEW','SYSTEM VIEW',o1.object_type),'SYSTEM',decode(o1.object_type,'TABLE','SYSTEM TABLE','VIEW','SYSTEM VIEW',o1.object_type),o1.object_type) table_type, null table_guid, null description, null table_propid, null date_created, null date_modified from all_objects o1 where o1.object_type in ('TABLE','VIEW')union select null table_catalog, decode (o2.owner, 'PUBLIC', NULL, o2.owner) table_schema, o2.object_name table_name, o2.object_type table_type, null table_guid, null description, null table_propid, null date_created, null date_modified from all_objects o2, all_objects o3, all_synonyms s where o2.object_type = 'SYNONYM' and o3.object_type in ('TABLE','VIEW') and o2.owner = s.owner and o2.object_name = s.synonym_name and s.table_owner = o3.owner and s.table_name = o3.object_name) tables order by 4,2,3
Has anybody an idea how I can limit the results of this query? It's not an option to change the query itself, because its executed by Visual Studio, I was thinking to revoke some rights for my student accounts, but I'm no expert, so ...
PS: my student accounts have standard roles CONNECT and RESOURCE
thanks in advance,
Kris Hermans.
instructor
http://www.xios.be

Answer 1

I think you are on the right track with revoking rights. The query you listed refers to all_tables -- which is the list of all the tables that the person executing the query has access to.
But to accomplish your goal, you would have to know more about the users and roles that they are doing. The view all_tab_privs shows you a list of tables and the privilege level for each grantee. You would have to revoke their select (and other) privs in order to stop them from showing up in the all_tables view.
But be careful....