Sunday, September 25, 2016

Oracle PLSQL - Advantages of Using Packages

Advantages of Using Packages

Packages provide an alternative to creating procedures and functions as stand-alone
schema objects, and they offer several benefits.

Modularity and ease of maintenance: You encapsulate logically related programming
structures in a named module. Each package is easy to understand, and the interface
between packages is simple, clear, and well defined.

Easier application design: All you need initially is the interface information in the
package specification. You can code and compile a specification without its body. Then
stored subprograms that reference the package can compile as well. You need not define
the package body fully until you are ready to complete the application.

Hiding information: You decide which constructs are public (visible and accessible) and
which are private (hidden and inaccessible). Declarations in the package specification are
visible and accessible to applications. The package body hides the definition of the private
constructs, so that only the package is affected (not your application or any calling
programs) if the definition changes. This enables you to change the implementation
without having to recompile the calling programs. Also, by hiding implementation details
from users, you protect the integrity of the package.

Added functionality: Packaged public variables and cursors persist for the duration of a
session. Thus, they can be shared by all subprograms that execute in the environment.
They also enable you to maintain data across transactions without having to store it in the
database. Private constructs also persist for the duration of the session but can be accessed
only within the package.

Better performance: When you call a packaged subprogram the first time, the entire
package is loaded into memory. Later calls to related subprograms in the package
therefore require no further disk I/O. Packaged subprograms also stop cascading
dependencies and thus avoid unnecessary compilation.

Overloading: With packages, you can overload procedures and functions, which means
you can create multiple subprograms with the same name in the same package, each taking
parameters of different number or data type.

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