5 Authorization: Privileges, Roles, Profiles, and Resource Limitations

5.1.1.1 Granting and Revoking System Privileges

You can grant or revoke system privileges to users and roles. If you grant system privileges to roles, then you can use the roles to manage system privileges. For example, roles permit privileges to be made selectively available.

Use either of the following to grant or revoke system privileges to users and roles:

• The Oracle Enterprise Manager 10g Database Control

• The GRANT and REVOKE SQL statements

  See Also:

  • For more information about Database Control, see Oracle Database 2 Day DBA.

  • For information about modifying users with Database Control, see the topic "Creating, Editing, and Deleting Users" in the Enterprise Manager online help.

5.1.1.2 Who Can Grant or Revoke System Privileges?

Only two types of users can grant system privileges to other users or revoke such privileges from them:

• Users who have been granted a specific system privilege with the ADMIN OPTION

• Users with the system privilege GRANT ANY PRIVILEGE

5.1.2.1 Granting and Revoking Schema Object Privileges

Schema object privileges can be granted to and revoked from users and roles. If you grant object privileges to roles, then you can make the privileges selectively available.

Object privileges for users and roles can be granted or revoked using the following:

• The SQL statements GRANT and REVOKE

• The Oracle Enterprise Manager 10g Database Control

  See Also:

  • For more information about Database Control, see Oracle Database 2 Day DBA.

  • For information about modifying privileges with Database Control, see the Enterprise Manager online help.

5.1.2.2 Who Can Grant Schema Object Privileges?

A user automatically has all object privileges for schema objects contained in his or her schema. A user can grant any object privilege on any schema object he or she owns to any other user or role. A user with the GRANT ANY OBJECT PRIVILEGE can grant or revoke any specified object privilege to another user with or without the GRANT OPTION of the GRANT statement. Otherwise, the grantee can use the privilege, but cannot grant it to other users.

For example, assume user SCOTT owns a table named t2:

SQL>GRANT GRANT ANY OBJECT PRIVILEGE TO u1; 
SQL> CONNECT u1/u1 
Connected. 
SQL> GRANT SELECT ON scott.t2 TO u2; 
SQL> SELECT GRANTEE, OWNER, GRANTOR, PRIVILEGE, GRANTABLE FROM DBA_TAB_PRIVS 
 WHERE TABLE_NAME = 'employees'; 

GRANTEE                        OWNER 
------------------------------ ------------------------------ 
GRANTOR                        PRIVILEGE                                GRA 
------------------------------ ---------------------------------------- --- 
U2                             SCOTT 
SCOTT                          SELECT                                   NO  

5.1.2.3 Using Privileges with Synonyms

A schema object and its synonym are equivalent with respect to privileges. That is, the object privileges granted for a table, view, sequence, procedure, function, or package apply whether referencing the base object by name or by using a synonym.

For example, assume there is a table jward.emp with a synonym named jward.employee, and the user jward issues the following statement:

GRANT SELECT ON emp TO swilliams; 

The user swilliams can query jward.emp by referencing the table by name or by using the synonym jward.employee:

SELECT * FROM jward.emp; 
SELECT * FROM jward.employee; 

If you grant object privileges on a table, view, sequence, procedure, function, or package to a synonym for the object, then the effect is the same as if no synonym were used. For example, if jward wanted to grant the SELECT privilege for the emp table to swilliams, then jward could issue either of the following statements:

GRANT SELECT ON emp TO swilliams; 
GRANT SELECT ON employee TO swilliams; 

If a synonym is dropped, then all grants for the underlying schema object remain in effect, even if the privileges were granted by specifying the dropped synonym.

5.1.3.1 DML Operations

You can grant privileges to use the DELETE, INSERT, SELECT, and UPDATE DML operations on a table or view. Grant these privileges only to users and roles that need to query or manipulate data in a table.

You can restrict INSERT and UPDATE privileges for a table to specific columns of the table. With selective INSERT, a privileged user can insert a row with values for the selected columns. All other columns receive NULL or the default value of the column. With selective UPDATE, a user can update only specific column values of a row. Selective INSERT and UPDATE privileges are used to restrict user access to sensitive data.

For example, if you do not want data entry users to alter the salary column of the employees table, then selective INSERT or UPDATE privileges can be granted that exclude the salary column. Alternatively, a view that excludes the salary column could satisfy this need for additional security.

5.1.3.2 DDL Operations

The ALTER, INDEX, and REFERENCES privileges allow DDL operations to be performed on a table. Because these privileges allow other users to alter or create dependencies on a table, you should grant privileges conservatively.

A user attempting to perform a DDL operation on a table may need additional system or object privileges. For example, to create a trigger on a table, the user requires both the ALTER TABLE object privilege for the table and the CREATE TRIGGER system privilege.

As with the INSERT and UPDATE privileges, the REFERENCES privilege can be granted on specific columns of a table. The REFERENCES privilege enables the grantee to use the table on which the grant is made as a parent key to any foreign keys that the grantee wishes to create in his or her own tables. This action is controlled with a special privilege because the presence of foreign keys restricts the data manipulation and table alterations that can be done to the parent key. A column-specific REFERENCES privilege restricts the grantee to using the named columns (which, of course, must include at least one primary or unique key of the parent table).

5.1.4.1 Privileges Required to Create Views

To create a view, you must meet the following requirements:

• You must have been granted one of the following system privileges, either explicitly or through a role:

  • The CREATE VIEW system privilege (to create a view in your schema)

  • The CREATE ANY VIEW system privilege (to create a view in another user's schema)

• You must have been explicitly granted one of the following privileges:

  • The SELECT, INSERT, UPDATE, or DELETE object privileges on all base objects underlying the view

  • The SELECT ANY TABLE, INSERT ANY TABLE, UPDATE ANY TABLE, or DELETE ANY TABLE system privileges

• In addition, in order to grant other users access to your view, you must have received object privileges to the base objects with the GRANT OPTION clause or appropriate system privileges with the ADMIN OPTION clause. If you have not, then grantees cannot access your view.

  See Also:

  Oracle Database SQL Reference

5.1.4.2 Increasing Table Security with Views

To use a view, you require appropriate privileges only for the view itself. You do not require privileges on base objects underlying the view.

Views add two more levels of security for tables, column-level security and value-based security:

• A view can provide access to selected columns of base tables. For example, you can define a view on the employees table to show only the employee_id, last_name, and manager_id columns:

  CREATE VIEW employees_manager AS 
      SELECT last_name, employee_id, manager_id FROM employees; 
  

• A view can provide value-based security for the information in a table. A WHERE clause in the definition of a view displays only selected rows of base tables. Consider the following two examples:

  CREATE VIEW lowsal AS 
      SELECT * FROM employees 
      WHERE salary < 10000; 
  

  The LOWSAL view allows access to all rows of the employees table that have a salary value less than 10000. Notice that all columns of the employees table are accessible in the LOWSAL view.

  CREATE VIEW own_salary AS 
      SELECT last_name, salary 
      FROM employees 
      WHERE last_name = USER; 
  

  In the own_salary view, only the rows with an last_name that matches the current user of the view are accessible. The own_salary view uses the user pseudocolumn, whose values always refer to the current user. This view combines both column-level security and value-based security.

5.1.5.1 Procedure Execution and Security Domains

A user with the EXECUTE object privilege for a specific procedure can execute the procedure or compile a program unit that references the procedure. No run-time privilege check is made when the procedure is called. A user with the EXECUTE ANY PROCEDURE system privilege can execute any procedure in the database. Privileges to execute procedures can be granted to a user through roles.

The owner of a procedure, called the definer, must have all the necessary object privileges for referenced objects. If the owner grants to another user the right to use that procedure, then the owner object privileges for the objects referenced by the procedure apply to that user's exercise of the procedure. These are termed "definer's rights."

The user of a procedure who is not its owner is called the "invoker." Additional privileges on referenced objects are required for invoker's rights procedures, but not for definer's rights procedures.

Definer's Rights

A user of a definer's rights procedure requires only the privilege to execute the procedure and no privileges on the underlying objects that the procedure accesses, because a definer's rights procedure operates under the security domain of the user who owns the procedure, regardless of who is executing it. The owner of the procedure must have all the necessary object privileges for referenced objects. Fewer privileges have to be granted to users of a definer's rights procedure, resulting in tighter control of database access.

You can use definer's rights procedures to control access to private database objects and add a level of database security. By writing a definer's rights procedure and granting only EXECUTE privilege to a user, the user can be forced to access the referenced objects only through the procedure.

At run-time, the privileges of the owner of a definer's rights stored procedure are always checked before the procedure is executed. If a necessary privilege on a referenced object has been revoked from the owner of a definer's rights procedure, then the procedure cannot be executed by the owner or any other user.

Invoker's Rights

An invoker's rights procedure executes with all of the invoker's privileges. Roles are enabled unless the invoker's rights procedure was called directly or indirectly by a definer's rights procedure. A user of an invoker's rights procedure needs privileges (either directly or through a role) on objects that the procedure accesses through external references that are resolved in the invoker's schema.

The invoker needs privileges at run-time to access program references embedded in DML statements or dynamic SQL statements, because they are effectively recompiled at run-time.

For all other external references, such as direct PL/SQL function calls, the owner's privileges are checked at compile time, and no run-time check is made. Therefore, the user of an invoker's rights procedure needs no privileges on external references outside DML or dynamic SQL statements. Alternatively, the developer of an invoker's rights procedure only needs to grant privileges on the procedure itself, not on all objects directly referenced by the invoker's rights procedure.

You can create a software bundle that consists of multiple program units, some with definer's rights and others with invoker's rights, and restrict the program entry points (controlled step-in). A user who has the privilege to execute an entry-point procedure can also execute internal program units indirectly, but cannot directly call the internal programs.

5.1.5.2 System Privileges Needed to Create or Alter a Procedure

To create a procedure, a user must have the CREATE PROCEDURE or CREATE ANY PROCEDURE system privilege. To alter a procedure, that is, to manually recompile a procedure, a user must own the procedure or have the ALTER ANY PROCEDURE system privilege.

The user who owns the procedure also must have privileges for schema objects referenced in the procedure body. To create a procedure, you must have been explicitly granted the necessary privileges (system or object) on all objects referenced by the procedure. You cannot have obtained the required privileges through roles. This includes the EXECUTE privilege for any procedures that are called inside the procedure being created.

5.1.5.3 Packages and Package Objects

A user with the EXECUTE object privilege for a package can execute any public procedure or function in the package and access or modify the value of any public package variable. Specific EXECUTE privileges cannot be granted for individual constructs in a package. Therefore, you may find it useful to consider two alternatives for establishing security when developing procedures, functions, and packages for a database application. These alternatives are described in the following examples.

Packages and Package Objects: Example 1

This example shows four procedures created in the bodies of two packages. 

CREATE PACKAGE BODY hire_fire AS 
  PROCEDURE hire(...) IS 
    BEGIN 
      INSERT INTO employees . . . 
    END hire; 
  PROCEDURE fire(...) IS 
    BEGIN 
      DELETE FROM employees . . . 
    END fire; 
END hire_fire; 

CREATE PACKAGE BODY raise_bonus AS 
  PROCEDURE give_raise(...) IS 
    BEGIN 
      UPDATE employees SET salary = . . . 
    END give_raise; 
  PROCEDURE give_bonus(...) IS 
    BEGIN 
      UPDATE employees SET bonus = . . . 
    END give_bonus; 
END raise_bonus; 

Access to execute the procedures is given by granting the EXECUTE privilege for the package by using the following statements:

GRANT EXECUTE ON hire_fire TO big_bosses; 
GRANT EXECUTE ON raise_bonus TO little_bosses; 

Packages and Package Objects: Example 2

This example shows four procedure definitions within the body of a single package. Two additional standalone procedures and a package are created specifically to provide access to the procedures defined in the main package.

CREATE PACKAGE BODY employee_changes AS 
  PROCEDURE change_salary(...) IS BEGIN ... END; 
  PROCEDURE change_bonus(...) IS BEGIN ... END; 
  PROCEDURE insert_employee(...) IS BEGIN ... END; 
  PROCEDURE delete_employee(...) IS BEGIN ... END; 
END employee_changes; 
 
CREATE PROCEDURE hire 
  BEGIN 
    employee_changes.insert_employee(...) 
  END hire; 
 
CREATE PROCEDURE fire 
  BEGIN 
    employee_changes.delete_employee(...) 
  END fire; 
 
PACKAGE raise_bonus IS 
  PROCEDURE give_raise(...) AS 
    BEGIN 
      employee_changes.change_salary(...) 
    END give_raise; 
 
  PROCEDURE give_bonus(...) 
    BEGIN 
      employee_changes.change_bonus(...) 
    END give_bonus; 

Using this method, the procedures that actually do the work (the procedures in the employee_changes package) are defined in a single package and can share declared global variables, cursors, on so on. By declaring top-level procedures, hire and fire, and an additional package, raise_bonus, you can grant selective EXECUTE privileges on procedures in the main package:

GRANT EXECUTE ON hire, fire TO big_bosses; 
GRANT EXECUTE ON raise_bonus TO little_bosses; 

5.1.6.1 System Privileges for Named Types

Oracle defines system privileges shown in Table 5-1 for named types (object types, VARRAYs, and nested tables):

The RESOURCE role includes the CREATE TYPE system privilege. The DBA role includes all of these privileges.

5.1.6.2 Object Privileges

The only object privilege that applies to named types is EXECUTE. If the EXECUTE privilege exists on a named type, then a user can use the named type to:

• Define a table

• Define a column in a relational table

• Declare a variable or parameter of the named type

The EXECUTE privilege permits a user to invoke the methods in the type, including the type constructor. This is similar to EXECUTE privilege on a stored PL/SQL procedure.

5.1.6.3 Method Execution Model

Method execution is the same as any other stored PL/SQL procedure.

5.1.6.4 Privileges Required to Create Types and Tables Using Types

To create a type, you must meet the following requirements:

• You must have the CREATE TYPE system privilege to create a type in your schema or the CREATE ANY TYPE system privilege to create a type in the schema of another user. These privileges can be acquired explicitly or through a role.

• The owner of the type must be explicitly granted the EXECUTE object privileges to access all other types referenced within the definition of the type, or have been granted the EXECUTE ANY TYPE system privilege. The owner cannot have obtained the required privileges through roles.

• If the type owner intends to grant access to the type to other users, then the owner must have received the EXECUTE privileges to the referenced types with the GRANT OPTION or the EXECUTE ANY TYPE system privilege with the ADMIN OPTION. If not, then the type owner has insufficient privileges to grant access on the type to other users.

To create a table using types, you must meet the requirements for creating a table and the following additional requirements:

• The owner of the table must have been explicitly granted the EXECUTE object privileges to access all types referenced by the table, or have been granted the EXECUTE ANY TYPE system privilege. The owner cannot have obtained the required privileges through roles.

• If the table owner intends to grant access to the table to other users, then the owner must have received the EXECUTE privileges to the referenced types with the GRANT OPTION or the EXECUTE ANY TYPE system privilege with the ADMIN OPTION. If not, then the table owner has insufficient privileges to grant access on the type to other users.

  See Also:

  "Table Privileges" for the requirements for creating a table

5.1.6.5 Example of Privileges for Creating Types and Tables Using Types

Assume that three users exist with the CONNECT and RESOURCE roles:

• user1

• user2

• user3

User1 performs the following DDL in his schema:

CREATE TYPE type1 AS OBJECT (
  attr1 NUMBER);

CREATE TYPE type2 AS OBJECT (
  attr2 NUMBER);

GRANT EXECUTE ON type1 TO user2;
GRANT EXECUTE ON type2 TO user2 WITH GRANT OPTION;

User2 performs the following DDL in his schema:

CREATE TABLE tab1 OF user1.type1;
CREATE TYPE type3 AS OBJECT (
  attr3 user1.type2);
CREATE TABLE tab2 (
  col1 user1.type2);

The following statements succeed because user2 has EXECUTE privilege on user1.type2 with the GRANT OPTION:

GRANT EXECUTE ON type3 TO user3;
GRANT SELECT on tab2 TO user3;

However, the following grant fails because user2 does not have EXECUTE privilege on user1.type1 with the GRANT OPTION:

GRANT SELECT ON tab1 TO user3;

User3 can successfully perform the following statements:

CREATE TYPE type4 AS OBJECT (
  attr4 user2.type3);
CREATE TABLE tab3 OF type4;

5.1.6.6 Privileges on Type Access and Object Access

Existing column-level and table-level privileges for DML statements apply to both column objects and row objects. Oracle defines the privileges shown in Table 5-2 for object tables.

Similar table privileges and column privileges apply to column objects. Retrieving instances does not in itself reveal type information. However, clients must access named type information in order to interpret the type instance images. When a client requests such type information, Oracle Database checks for EXECUTE privilege on the type.

Consider the following schema:

CREATE TYPE emp_type (
    eno NUMBER, ename CHAR(31), eaddr addr_t);
CREATE TABLE emp OF emp_t;

In addition, consider the following two queries:

SELECT VALUE(emp) FROM emp;
SELECT eno, ename FROM emp;

For either query, Oracle Database checks the SELECT privilege of the user for the emp table. For the first query, the user needs to obtain the emp_type type information to interpret the data. When the query accesses the emp_type type, Oracle checks the EXECUTE privilege of the user.

Execution of the second query, however, does not involve named types, so Oracle does not check type privileges.

In addition, by using the schema from the previous section, user3 can perform the following queries:

SELECT tab1.col1.attr2 FROM user2.tab1 tab1;
SELECT attr4.attr3.attr2 FROM tab3;

Note that in both SELECT statements, user3 does not have explicit privileges on the underlying types, but the statement succeeds because the type and table owners have the necessary privileges with the GRANT OPTION.

Oracle Database checks privileges on the following events and returns an error if the client does not have the privilege for the action:

• Pinning an object in the object cache using its REF value causes Oracle Database to check for the SELECT privilege on the containing object table.

• Modifying an existing object or flushing an object from the object cache causes Oracle Database to check for the UPDATE privilege on the destination object table.

• Flushing a new object causes Oracle Database to check for the INSERT privilege on the destination object table.

• Deleting an object causes Oracle Database to check for the DELETE privilege on the destination table.

• Pinning an object of a named type causes Oracle to check EXECUTE privilege on the object.

Modifying the attributes of an object in a client third-generation language application causes Oracle Database to update the entire object. Therefore, the user needs UPDATE privilege on the object table. Having the UPDATE privilege on only certain columns of the object table is not sufficient, even if the application only modifies attributes corresponding to those columns. Therefore, Oracle Database does not support column-level privileges for object tables.

5.1.6.7 Type Dependencies

As with stored objects, such as procedures and tables, types being referenced by other objects are called dependencies. There are some special issues for types that tables depend on. Because a table contains data that relies on the type definition for access, any change to the type causes all stored data to become inaccessible. Changes that can cause this are when necessary privileges required by the type are revoked or the type or dependent types are dropped. If either of these actions occur, then the table becomes invalid and cannot be accessed.

A table that is invalid because of missing privileges can automatically become valid and accessible if the required privileges are granted again. A table that is invalid because a dependent type has been dropped can never be accessed again, and the only permissible action is to drop the table.

Because of the severe effects that revoking a privilege on a type or dropping a type can cause, the SQL statements REVOKE and DROP TYPE, by default, implement a restrict semantics. This means that if the named type in either statement has table or type dependents, then an error is received and the statement aborts. However, if the FORCE clause for either statement is used, then the statement always succeeds. If there are depended-upon tables, then they are invalidated.

5.2.2.1 Application Roles

You grant an application role all privileges necessary to run a given database application. Then, you grant the secure application role to other roles or to specific users. An application can have several different roles, with each role assigned a different set of privileges that allow for more or less data access while using the application.

5.2.2.2 User Roles

You create a user role for a group of database users with common privilege requirements. You manage user privileges by granting secure application roles and privileges to the user role and then granting the user role to appropriate users.

5.2.3.1 Who Can Grant or Revoke Roles?

Any user with the GRANT ANY ROLE system privilege can grant or revoke any role except a global role to or from other users or roles of the database. You should grant this system privilege conservatively because it is very powerful.

Any user granted a role with the ADMIN OPTION can grant or revoke that role to or from other users or roles of the database. This option allows administrative powers for roles on a selective basis.

5.2.5.1 Named Blocks with Definer's Rights

All roles are disabled in any named PL/SQL block (stored procedure, function, or trigger) that executes with definer's rights. Roles are not used for privilege checking and you cannot set roles within a definer's rights procedure.

The SESSION_ROLES view shows all roles that are currently enabled. If a named PL/SQL block that executes with definer's rights queries SESSION_ROLES, then the query does not return any rows.

5.2.5.2 Anonymous Blocks with Invoker's Rights

Named PL/SQL blocks that execute with invoker's rights and anonymous PL/SQL blocks are executed based on privileges granted through enabled roles. Current roles are used for privilege checking within an invoker's rights PL/SQL block, and you can use dynamic SQL to set a role in the session.

5.2.10.1 Creation of Secure Application Roles

Secure application roles are created by using the statement CREATE ROLE ... IDENTIFIED USING. Here is an example:

CREATE ROLE admin_role IDENTIFIED USING hr.admin;

This statement indicates the following:

• The role admin_role to be created is a secure application role.

• The role can only be enabled by modules defined inside the PL/SQL package hr.admin.

You must have the CREATE ROLE system privilege to execute this statement.

When such a role is assigned to a user, it becomes a default role for that user, which is automatically enabled at login without resorting to the package. A user with a default role does not have to be authenticated in any way to use the role. For example, the password for the role is not requested or required.

To restrict the role solely to the use specified by the IDENTIFIED USING clause, you can take either of the following actions:

• Immediately after granting such a role to a user, issue an ALTER USER statement with the clause DEFAULT ROLE ALL EXCEPT role, substituting the application role for role. Then role can only be used by applications executing the authorized package.

• When assigning roles, use GRANT ALL EXCEPT role.

Roles that are enabled inside an invoker's right procedure remain in effect even after the procedure exits. Therefore, you can have a dedicated procedure that deals with enabling the role for the rest of the session to use.

5.3.1.1 Session Level

Each time a user connects to a database, a session is created. Each session consumes CPU time and memory on the computer that runs Oracle Database. You can set several resource limits at the session level.

If a user exceeds a session-level resource limit, then Oracle terminates (rolls back) the current statement and returns a message indicating that the session limit has been reached. At this point, all previous statements in the current transaction are intact, and the only operations the user can perform are COMMIT, ROLLBACK, or disconnect (in this case, the current transaction is committed). All other operations produce an error. Even after the transaction is committed or rolled back, the user can accomplish no more work during the current session.

5.3.1.2 Call Level

Each time a SQL statement is executed, several steps are taken to process the statement. During this processing, several calls are made to the database as a part of the different execution phases. To prevent any one call from using the system excessively, Oracle Database lets you set several resource limits at the call level.

If a user exceeds a call-level resource limit, then Oracle Database halts the processing of the statement, rolls back the statement, and returns an error. However, all previous statements of the current transaction remain intact, and the user session remains connected.

5.3.1.3 CPU Time

When SQL statements and other types of calls are made to Oracle Database, a certain amount of CPU time is necessary to process the call. Average calls require a small amount of CPU time. However, a SQL statement involving a large amount of data or a runaway query can potentially consume a large amount of CPU time, reducing CPU time available for other processing.

To prevent uncontrolled use of CPU time, you can set fixed or dynamic limits on the CPU time for each call and the total amount of CPU time used for Oracle calls during a session. The limits are set and measured in CPU one-hundredth seconds (0.01 seconds) used by a call or a session.

5.3.1.4 Logical Reads

I/O is one of the most expensive operations in a database system. SQL statements that are I/O-intensive can monopolize memory and disk use and cause other database operations to compete for these resources.

To prevent single sources of excessive I/O, Oracle Database lets you limit the logical data block reads for each call and for each session. Logical data block reads include data block reads from both memory and disk. The limits are set and measured in number of block reads performed by a call or during a session.

5.3.1.5 Limiting Other Resources

Oracle Database also provides for limiting several other resources at the session level:

• You can limit the number of concurrent sessions for each user. Each user can create only up to a predefined number of concurrent sessions.

• You can limit the idle time for a session. If the time between calls in a session reaches the idle time limit, then the current transaction is rolled back, the session is aborted, and the resources of the session are returned to the system. The next call receives an error that indicates that the user is no longer connected to the instance. This limit is set as a number of elapsed minutes.

  Note:

  Shortly after a session is aborted because it has exceeded an idle time limit, the process monitor (PMON) background process cleans up after the aborted session. Until PMON completes this process, the aborted session is still counted in any session or user resource limit.

• You can limit the elapsed connect time for each session. If the duration of a session exceeds the elapsed time limit, then the current transaction is rolled back, the session is dropped, and the resources of the session are returned to the system. This limit is set as a number of elapsed minutes.

  Note:

  Oracle Database does not constantly monitor the elapsed idle time or elapsed connection time. Doing so would reduce system performance. Instead, it checks every few minutes. Therefore, a session can exceed this limit slightly (for example, by five minutes) before Oracle enforces the limit and aborts the session.

• You can limit the amount of private System Global Area (SGA) space (used for private SQL areas) for a session. This limit is only important in systems that use the shared server configuration. Otherwise, private SQL areas are located in the Program Global Area (PGA). This limit is set as a number of bytes of memory in the SGA of an instance. Use the characters K or M to specify kilobytes or megabytes.

  See Also:

  For instructions on enabling or disabling resource limits:

  • Viewing Information About Database Users and Profiles

  • Managing User Roles

  • Oracle Database Administrator's Guide