What is copy and Nocopy in Oracle?
The NOCOPY hint tells the PL/SQL compiler to pass OUT and IN OUT parameters by reference, rather than by value. The process of copying large parameters, such as records, collections, and objects requires both time and memory which affects performance.
What is Nocopy clause where it is used?
The final point to cover in passing variables is the NOCOPY clause . When a parameter is passed as an IN variable, it is passed by reference. The NOCOPY clause tells to PL/SQL engine to pass the variable by reference, thus avoiding the cost of copying the variable at the end of the procedure.
When a parameter to the procedure is passes using Nocopy option?
Pass By Reference : Using the NOCOPY hint tells the compiler to use pass by reference, so no temporary buffer is needed and no copy forward and copy back operations happen. Instead, any modification to the parameter values are written directly to the parameter variable (actual parameter).
When a parameter to the procedure is passed using Nocopy option the modification done to the formal parameter is reflected in actual parameter?
IN parameters are always passed by reference. When a parameter is passed by reference, the formal and actual parameters refer to the same memory location. Any changes to the value of the formal parameter are immediately reflected in the actual parameter as well.
Which of the following is true for Nocopy option in SQL?
So when should you use NOCOPY? Use NOCOPY when both of these conditions are true: the OUT or IN OUT parameters of a subprogram use large data structures causing performance issues in parameter passing. the calling program can ignore the parameter values returned by the subprogram if the subprogram exits with error.
What are packages in Oracle SQL?
A package is a schema object that groups logically related PL/SQL types, variables, constants, subprograms, cursors, and exceptions. A package is compiled and stored in the database, where many applications can share its contents.
What are the three parameter modes for procedures?
PL/SQL procedure parameters can have one of three possible modes: IN, OUT, or IN OUT. PL/SQL function parameters can only be IN. An IN formal parameter is initialized to the actual parameter with which it was called, unless it was explicitly initialized with a default value.
What are the parameter passing techniques to function with example?
There are two ways to pass parameters in C: Pass by Value, Pass by Reference.
- Pass by Value. Pass by Value, means that a copy of the data is made and stored by way of the name of the parameter.
- Pass by Reference. A reference parameter “refers” to the original data in the calling function.
What is ref cursor in Oracle with example?
A REF CURSOR is a PL/SQL data type whose value is the memory address of a query work area on the database. In essence, a REF CURSOR is a pointer or a handle to a result set on the database. REF CURSOR s are represented through the OracleRefCursor ODP.NET class.
What is package in SQL explain with example?
What is procedure in Oracle with example?
Procedure Vs. Function: Key Differences
| Procedure | Function |
|---|---|
| Used mainly to a execute certain process | Used mainly to perform some calculation |
| Cannot call in SELECT statement | A Function that contains no DML statements can be called in SELECT statement |
| Use OUT parameter to return the value | Use RETURN to return the value |
What is a NOCOPY parameter in Oracle?
Where OUT and IN OUT are implemented as copy out and copy-in/copy out respectively, NOCOPY directs the compiler to not create a copy of a variable. It rather passes it as a reference. – It requests that the compiler pass the corresponding actual parameter by reference instead of value.
Which is an example of the use of NOCOPY?
For example: In the absence of the NOCOPY hint the entire orders collection would have been copied into the theorders variable upon exit from the procedure. Instead the collection is now passed by reference. Keep in mind, however, that there is a downside to using NOCOPY.
Why do we use NOCOPY hint in PLSQL?
The NOCOPY hint allows the PLSQL compiler to pass OUT and IN OUT parameters by reference rather than by value. The reason behind passing the parameters by reference is to improve the performance of PL SQL code. It reduces the overhead of passing parameters.
When to use the NOCOPY clause in SQL?
The NOCOPY clause tells to PL/SQL engine to pass the variable by reference, thus avoiding the cost of copying the variable at the end of the procedure. The PL/SQL engine has requirements that must be met before passing the variable by reference and if those requirements are not met, the NOCOPY clause will simply be ignored by the PL/SQL engine.
