Stored program units (also known as stored subprograms, or stored procedures) can be compiled separately and stored permanently in an Oracle database, ready to be executed. Once compiled and stored in the data dictionary, they are schema objects, which can be referenced by any number of applications connected to that database.
Stored program units offer higher productivity, better performance, memory savings, application integrity, and tighter security. For example, by designing applications around a library of stored procedures and functions, you can avoid redundant coding and increase your productivity.
Stored program units are stored in parsed, compiled form. So, when called, they are loaded and passed to the PL/SQL engine immediately. Also, they take advantage of shared memory. So, only one copy of a program unit need be loaded into memory for execution by multiple users.
Because stored program units run in ORACLE, they can perform database operations more quickly than PL/SQL that is local to your report. Therefore, in general, use stored program units for PL/SQL that performs database operations. Use local program units for PL/SQL that does not involve database operations. However, if you are on a heavily loaded network with very slow response time, using stored program units may not be faster for database operations. Similarly, if your server is significantly faster than your local machine, then using local program units may not be faster for non-database operations.
Creating a stored program unit
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