Is there a way to access object from other schema?

Question

1. Is there a way to access object from other schema
Without using synonym/public synonym without prefixing schema owner?
2. If you do not see any object in all_objects by same name owned by connected user or public, can there still be objects hidden from this view? for instance synonyms created by SYSTEM
TIA for help

Answer 1

Well, you missed something somewhere. If there is no
ALTER SESSION SET CURRENT_SCHEMA=whoeverthen there must be either public synonym for the object as this shows:
SQL> CREATE USER a identified by a;
User created.
SQL> GRANT CREATE SESSION to a;
Grant succeeded.
SQL> CREATE USER b identified by b;
User created.
SQL> GRANT CREATE SESSION, CREATE PROCEDURE, CREATE PUBLIC SYNONYM to b;
Grant succeeded.
SQL> connect b/b
Connected.
SQL> CREATE PACKAGE test AS
  2     PROCEDURE testit;
  3  END;
  4  /
Package created.
SQL> CREATE PACKAGE BODY test AS
  2  PROCEDURE testit IS
  3  BEGIN
  4     NULL;
  5  END;
  6  END;
  7  /
Package body created.
SQL> connect a/a
Connected.
SQL> desc b.test
ERROR:
ORA-04043: object b.test does not exist
SQL> connect b/b
Connected.
SQL> GRANT EXECUTE ON test TO a;
Grant succeeded.
SQL> connect a/a
Connected.
SQL> desc b.test;
PROCEDURE TESTIT
SQL> desc test;
ERROR:
ORA-04043: object test does not exist
SQL> connect b/b
Connected.
SQL> CREATE PUBLIC SYNONYM test FOR TEST;
Synonym created.
SQL> connect a/a
Connected.
SQL> desc test
PROCEDURE TESTITAnother possibility without public synonyms is that crv had granted the other user privileges on some object, and the other user creates a private synonym for that. When crv granted privileges on a different object with the same name, the private synonym became valid again. Something like:
SQL> connect /
Connected.
SQL> drop public synonym test;
Synonym dropped.
SQL> GRANT CREATE SYNONYM TO a;
Grant succeeded.
SQL> connect a/a
Connected.
SQL> desc test;
ERROR:
ORA-04043: object test does not exist
SQL> desc b.test
PROCEDURE TESTIT
SQL> CREATE SYNONYM test FOR b.test;
Synonym created.
SQL> desc test;
PROCEDURE TESTIT
SQL> connect b/b
Connected.
SQL> REVOKE EXECUTE ON test FROM a;
Revoke succeeded.
SQL> connect a/a
Connected.
SQL> desc test;
ERROR:
ORA-04043: object "B"."TEST" does not exist
SQL> desc b.test
ERROR:
ORA-04043: object b.test does not exist
SQL> connect b/b
Connected.
SQL> DROP PACKAGE test;
Package dropped.
SQL> CREATE FUNCTION test (p_num IN NUMBER) RETURN NUMBER AS
  2  BEGIN
  3     RETURN p_num * 10;
  4  END;
  5  /
Function created.
SQL> GRANT EXECUTE ON test TO a;
Grant succeeded.
SQL> connect a/a
Connected.
SQL> desc test;
FUNCTION test RETURNS NUMBER
Argument Name                  Type                    In/Out Default?
P_NUM                          NUMBER                  INSo, I would go looking for the synonyms.
TTFN
John