The DBMS_OUTPUT.DISABLE procedure in Oracle Database is part of the DBMS_OUTPUT package, which is commonly used for debugging and displaying output from PL/SQL code blocks, procedures, and functions. The package provides a way for developers to collect debugging information or to print out a trace of execution steps in PL/SQL code.
When you execute PL/SQL blocks, procedures, or functions that include calls to DBMS_OUTPUT.PUT_LINE for displaying output, by default, this output is not visible unless you explicitly enable the server output in your session. This is typically done using the DBMS_OUTPUT.ENABLE procedure or by setting server output on in your client interface, such as SQL*Plus or SQL Developer, with commands like SET SERVEROUTPUT ON.
The DBMS_OUTPUT.DISABLE procedure is used to disable the buffer that stores messages for output. Once disabled, the PUT_LINE procedure calls will not queue messages for output, effectively silencing the output from DBMS_OUTPUT. This can be useful in production environments or in specific sections of code where output is no longer needed, and you wish to conserve memory by not filling up the output buffer.
Syntax
The syntax for DBMS_OUTPUT.DISABLE is straightforward, as it takes no parameters:
DBMS_OUTPUT.DISABLE;
Usage
Here is a simple example of how DBMS_OUTPUT.DISABLE might be used in a PL/SQL block:
BEGIN
DBMS_OUTPUT.ENABLE; -- Enable output
DBMS_OUTPUT.PUT_LINE('This message will be visible.');
DBMS_OUTPUT.DISABLE; -- Disable output
DBMS_OUTPUT.PUT_LINE('This message will not be visible.');
END;
In this example:
The first call to DBMS_OUTPUT.PUT_LINE will queue the message for output, because output has been enabled with DBMS_OUTPUT.ENABLE.
After DBMS_OUTPUT.DISABLE is called, the output is disabled, and subsequent calls to PUT_LINE will not queue messages for output. Thus, the second message will not be visible in the session’s output.
Considerations
Disabling DBMS_OUTPUT does not clear the buffer. If you want to clear the buffer, you should use DBMS_OUTPUT.PUT_BUFFER, which clears all messages currently stored in the buffer.
Remember to enable DBMS_OUTPUT if you wish to see output again after disabling it.
The visibility of output also depends on the client tool you are using and whether it supports displaying server output. Make sure your tool is configured appropriately to show or hide server output.
In summary, DBMS_OUTPUT.DISABLE is a useful procedure for controlling the visibility of debug and trace information in PL/SQL code, allowing developers to manage when and how much information is printed out during the execution of PL/SQL blocks.