ALTER FUNCTION Statement

The ALTER FUNCTION statement explicitly recompiles a standalone stored function. Explicit recompilation eliminates the need for implicit run-time recompilation and prevents associated run-time compilation errors and performance overhead.

Note:

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

Topics:

Prerequisites
Syntax
Semantics
Example
Related Topics

Prerequisites

If the function is in the SYS schema, you must be connected as SYSDBA. Otherwise, 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

The name of the schema containing the function. The default is your own schema.

function

The name of the function to be recompiled.

COMPILE

Recompiles the function, whether it is valid or invalid.

First, if any of the objects upon which the function depends are invalid, the database recompiles them.

The database also invalidates any local objects that depend upon the function, such as subprograms that call the recompiled function or package bodies that define subprograms that call the recompiled function.

If the database recompiles the function successfully, then the function becomes valid. Otherwise, the database returns an error and the function remains invalid.

During recompilation, the database drops all persistent compiler switch settings, retrieves them again from the session, and stores them after compilation. To avoid this process, specify the REUSE SETTINGS clause.

DEBUG

Has the same effect as PLSQL_OPTIMIZE_LEVEL=1—instructs the PL/SQL compiler to generate and store the code for use by the PL/SQL debugger. Oracle recommends using PLSQL_OPTIMIZE_LEVEL=1 instead of DEBUG.

compiler_parameters_clause

Specifies a value for one of the PL/SQL compilation parameters in Table 1-1. The compile-time value of each of these parameters is stored with the metadata of the PL/SQL unit being compiled.

You can specify each parameter only once in each statement. Each setting is valid only for the PL/SQL 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 PL/SQL unit, the database uses that earlier value. If you omit any parameter and either you do not specify REUSE SETTINGS or no value was specified for the parameter in an earlier compilation, then the database obtains the value for that parameter from the session environment.

REUSE SETTINGS

Prevents Oracle Database 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.

Example

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

ALTER FUNCTION oe.get_bal COMPILE;

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

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