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5.27 PLVtmr: Program Performance Analyzer

The PLVtmr (PL/Vision TiMeR) package allows you to measure the elapsed time of PL/SQL code; it provides a programmatic layter around the GET_TIME function of Oracle's DBMS_UTILITY package. See Chapter 14, PLVtmr: Analyzing Program Performance for details.

5.27.1 Control execution of timings

PROCEDURE turn_on;

Enables the timing package. All PLVtmr programs will execute as requested.

PROCEDURE turn_off;

Disables PLVtmr. Calls to timing programs will be ignored.

5.27.2 Setting the repetition value

PROCEDURE set_repeats (repeats_in IN NUMBER);

Sets the number of repetitions for all timing loops implemented inside the PLVtmr package ( calibrate , func , currsucc , currfail ).

FUNCTION repeats RETURN NUMBER;

Returns the current repetition value.

5.27.3 Setting the factoring value

PROCEDURE set_factor (factor_in IN NUMBER);

Sets the number of iterations when calling PLVtmr in a loop. This value allows PLVtmr to show total and individual elapsed times.

FUNCTION factor RETURN NUMBER;

Returns the current number of iterations.

5.27.4 Capturing the current timestamp

PROCEDURE capture (context_in IN VARCHAR2 := NULL);

Calls capture to capture the current timestamp (usually the start time of an elapsed time calculation). You can provide an optional context for the timing.

5.27.5 Retrieving and displaying elapsed time

FUNCTION elapsed RETURN NUMBER;

Returns the number of hundredths of seconds elapsed since last call to capture .

FUNCTION elapsed_message
(prefix_in IN VARCHAR2 := NULL,
adjust_in IN NUMBER := 0,
reset_in IN BOOLEAN := TRUE,
reset_context_in IN VARCHAR2 := NULL)
RETURN VARCHAR2;

Returns a standard message format around the value returned by elapsed .

PROCEDURE show_elapsed
(prefix_in IN VARCHAR2 := NULL,
adjust_in IN NUMBER := 0,
reset_in IN BOOLEAN := TRUE);

Displays the elapsed time message returned by elapsed_message .

5.27.6 Calibration and timing scripts

PLVtmr offers a set of predefined scripts and calibration programs to test comparative performances. You might find these particular programs useful; you might simply follow their example to construct your own.

PROCEDURE calibrate;

Calculates a base timing  -- the amount of time required to execute the NULL statement the current number of repetitions (set through set_repetitions ).

FUNCTION base_timing RETURN NUMBER;

Returns the current base timing.

PROCEDURE func;

Calculates the overhead of a function call.

PROCEDURE cursucc;

Compares the performance of implicit and explicit cursors when retrieving a row successfully.

PROCEDURE curfail;

Compares the performance of implicit and explicit cursors when failing to retrieve a row.


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