How to find those different namespaces in schema?

Question

Hi,
I heard that schema contains different name spaces. how to find those different namespaces in schema?
I checked with this but it is throwing "table or view doesn't exist".
select namespace from v$librarycache;
Thanks
Praveen

Answer 1

Are you referring to this? From the SQL Language Reference manual under Schema Object Names and Qualifiers
7. Within a namespace, no two objects can have the same name.
The following schema objects share one namespace:
Tables
Views
Sequences
Private synonyms
Stand-alone procedures
Stand-alone stored functions
Packages
Materialized views
User-defined types
Each of the following schema objects has its own namespace:
Indexes
Constraints
Clusters
Database triggers
Private database links
Dimensions
Because tables and views are in the same namespace, a table and a view in the same schema cannot have the same name. However, tables and indexes are in different namespaces. Therefore, a table and an index in the same schema can have the same name.
Each schema in the database has its own namespaces for the objects it contains. This means, for example, that two tables in different schemas are in different namespaces and can have the same name.
Each of the following nonschema objects also has its own namespace:
User roles
Public synonyms
Public database links
Tablespaces
Profiles
Parameter files (PFILEs) and server parameter files (SPFILEs)
Because the objects in these namespaces are not contained in schemas, these namespaces span the entire database.Which is why you can do:
SQL> create table t (id number, descr varchar2(10));
Table created.
SQL> alter table t add constraint t check (mod(id,2) = 0);
Table altered.
SQL> create index t on t(id);
Index created.
SQL> create trigger t
  2  before update on t
  3  begin
  4     dbms_output.put_line('T Trigger');
  5  end;
  6  /
Trigger created.but not:
SQL> create view t as select * from t;
create view t as select * from t
ERROR at line 1:
ORA-00955: name is already used by an existing objector
SQL> create procedure t
  2  begin
  3     null;
  4  end;
  5  /
create procedure t
ERROR at line 1:
ORA-00955: name is already used by an existing objectJohn