Oracle dbms_utility. Get_time and Dbms_utility. Get_cpu_time differences

Dbms_utility. Get_time and Dbms_utility. Get_cpu_time comparison

Original link:http://www.oracle-developer.net/display.php?id=307


developers have always been familiar with dbms_utility. The Get_time function. Common terms test the interval of 2 points in a program, that is, the program is time consuming.
To the 10g,oracle and add a dbms_utility. The Get_cpu_time function. This new function is used to measure the CPU time used at 2 points in time.
Let's illustrate the difference between the following 2 functions by using an example:

Example 1: A computationally intensive (cpu-bound) Type example

This example does not have I/O. This emphasizes CPU-intensive operations, in which case the get_time and Get_cpu_time functions will return almost consistent time-consuming.

DECLARE    B1 Pls_integer;    B2 Pls_integer;    E1 Pls_integer;    E2 Pls_integer;    n  Pls_integer: = 0; BEGIN    B1: = dbms_utility. Get_time ();    B2: = dbms_utility. Get_cpu_time ();    For I in 1.. 100000000 LOOP       --null;       N: = n + 1;    END LOOP;    E1: = dbms_utility. Get_time ()-B1;    E2: = Dbms_utility. Get_cpu_time ()-B2;    Dbms_output. Put_Line (' get_time elapsed = ' | | e1 | | ' Hsecs. ');    Dbms_output. Put_Line (' get_cpu_time elapsed = ' | | e2 | | ' Hsecs. '); END;

Get_time elapsed = 175 Hsecs.
Get_cpu_time elapsed = 174 hsecs.


The PL/SQL process has completed successfully.




Example 2:i/o dense (i/o-bound) Type example


This example is more representative of the Plsql program. In this case we will see that the 2 functions will take a different time.

DECLARE   B1 Pls_integer;   B2 Pls_integer;   E1 Pls_integer;   E2 Pls_integer; BEGIN   B1: = dbms_utility. Get_time ();   B2: = dbms_utility. Get_cpu_time ();   For R in (SELECT * from All_source) LOOP      NULL;   END LOOP;   E1: = dbms_utility. Get_time ()-B1;   E2: = Dbms_utility. Get_cpu_time ()-B2;   Dbms_output. Put_Line (' get_time elapsed = ' | | e1 | | ' Hsecs. ');   Dbms_output. Put_Line (' get_cpu_time elapsed = ' | | e2 | | ' Hsecs. '); end;/

Get_time elapsed = 324 Hsecs.
Get_cpu_time elapsed = 273 Hsecs.

The PL/SQL process has completed successfully.

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Dylan presents.

Oracle dbms_utility. Get_time and Dbms_utility. Get_cpu_time differences