ALTER FUNCTION

Purpose

Use the ALTER FUNCTION statement to recompile an invalid standalone stored function. Explicit recompilation eliminates the need for implicit run-time recompilation and prevents associated run-time compilation errors and performance overhead.

The ALTER FUNCTION statement is similar to ALTER PROCEDURE. For information on how Oracle Database recompiles functions and procedures, see Oracle Database Concepts.

This statement does not change the declaration or definition of an existing function. To redeclare or redefine a function, use the CREATE FUNCTION statement with the OR REPLACE clause. See CREATE FUNCTION.

Prerequisites

The function must be in your own schema or you must have ALTER ANY PROCEDURE system privilege.

Syntax

alter_function::=

Description of the illustration alter_function.gif

compiler_parameters_clause::=

Description of the illustration compiler_parameters_clause.gif

Semantics

schema

Specify the schema containing the function. If you omit schema, Oracle Database assumes the function is in your own schema.

function

Specify the name of the function to be recompiled.

COMPILE

Specify COMPILE to cause Oracle Database to recompile the function. The COMPILE keyword is required. If Oracle Database does not compile the function successfully, you can see the associated compiler error messages with the SQL*Plus command SHOW ERRORS.

During recompilation, Oracle Database drops all persistent compiler switch settings, retrieves them again from the session, and stores them at the end of compilation. To avoid this process, specify the REUSE SETTINGS clause.

DEBUG

Specify DEBUG to instruct the PL/SQL compiler to generate and store the code for use by the PL/SQL debugger. Specifying this clause has the same effect as specifying PLSQL_DEBUG = TRUE in the compiler_parameters_clause.

compiler_parameters_clause

Use this clause to specify a value for one of the PL/SQL persistent compiler parameters. The value of these initialization parameters at the time of compilation is stored with the unit's metadata. You can learn the value of such a parameter by querying the appropriate *_PLSQL_OBJECT_SETTINGS view. The PL/SQL persistent parameters are PLSQL_OPTIMIZE_LEVEL, PLSQL_CODE_TYPE, PLSQL_DEBUG, PLSQL_WARNINGS, PLSQL_CCFLAGS, and NLS_LENGTH_SEMANTICS.

You can specify each parameter only once in each statement. Each setting is valid only for the current library unit being compiled and does not affect other compilations in this session or system. To affect the entire session or system, you must set a value for the parameter using the ALTER SESSION or ALTER SYSTEM statement.

If you omit any parameter from this clause and you specify REUSE SETTINGS, then if a value was specified for the parameter in an earlier compilation of this library unit, Oracle Database uses that earlier value. If you omit any parameter and either you do not specify REUSE SETTINGS or no value has been specified for the parameter in an earlier compilation, then the database obtains the value for that parameter from the session environment.

Restriction on the compiler_parameters_clause  You cannot set a value for the PLSQL_DEBUG parameter if you also specify DEBUG, because both clauses set the PLSQL_DEBUG parameter, and you can specify a value for each parameter only once.

REUSE SETTINGS

Specify REUSE SETTINGS to prevent Oracle from dropping and reacquiring compiler switch settings. With this clause, Oracle preserves the existing settings and uses them for the recompilation of any parameters for which values are not specified elsewhere in this statement.

For backward compatibility, Oracle Database sets the persistently stored value of the PLSQL_COMPILER_FLAGS initialization parameter to reflect the values of the PLSQL_CODE_TYPE and PLSQL_DEBUG parameters that result from this statement.

Example

Recompiling a Function: Example To explicitly recompile the function get_bal owned by the sample user oe, issue the following statement:

ALTER FUNCTION oe.get_bal
   COMPILE; 

If Oracle Database encounters no compilation errors while recompiling get_bal, then get_bal becomes valid. Oracle Database can subsequently execute it without recompiling it at run time. If recompiling get_bal results in compilation errors, then Oracle Database returns an error, and get_bal remains invalid.

Oracle Database also invalidates all objects that depend upon get_bal. If you subsequently reference one of these objects without explicitly recompiling it first, then Oracle Database recompiles it implicitly at run time.