How bulk bind helps improvement in performance?, PL-SQL Programming

How Bulk Binds Improve Performance

The assigning of values to the PL/SQL variables in SQL statements is known as binding.

The binding of the whole collection at once is known as the bulk binding. The Bulk binds improve performance by minimizing the number of the context switches between the PL/SQL and SQL engines. With the bulk binds, whole collections, not just an individual element, are passed back and forth. For illustration, the DELETE statement below is sent to the SQL engine just once, with the whole nested table:

DECLARE

TYPE NumList IS TABLE OF NUMBER;

mgrs NumList := NumList(7566, 7782, ...); -- manager numbers

BEGIN

...

FORALL i IN mgrs.FIRST..mgrs.LAST

DELETE FROM emp WHERE mgr = mgrs(i);

END;

In the illustration below, 5000 part numbers and names are loaded into the index-by tables. Then, all the table elements are inserted into a database table twice. At First, they are inserted using a FOR loop, that completes in 38 seconds. Then, they are bulk-inserted by using a FORALL statement that completes in only 3 seconds.

SQL> SET SERVEROUTPUT ON

SQL> CREATE TABLE parts (pnum NUMBER(4), pname CHAR(15));

Table created.

SQL> GET test.sql

1 DECLARE

2 TYPE NumTab IS TABLE OF NUMBER(4) INDEX BY BINARY_INTEGER;

3 TYPE NameTab IS TABLE OF CHAR(15) INDEX BY BINARY_INTEGER;

4 pnums NumTab;

5 pnames NameTab;

6 t1 CHAR(5);

7 t2 CHAR(5);

8 t3 CHAR(5);

9 PROCEDURE get_time (t OUT NUMBER) IS

10 BEGIN SELECT TO_CHAR(SYSDATE,'SSSSS') INTO t FROM dual; END;

11 BEGIN

12 FOR j IN 1..5000 LOOP -- load index-by tables

13 pnums(j) := j;

14 pnames(j) := 'Part No. ' || TO_CHAR(j); 15 END LOOP;

16 get_time(t1);

17 FOR i IN 1..5000 LOOP -- use FOR loop

18 INSERT INTO parts VALUES (pnums(i), pnames(i));

19 END LOOP;

20 get_time(t2);

21 FORALL i IN 1..5000 -- use FORALL statement

22 INSERT INTO parts VALUES (pnums(i), pnames(i));

23 get_time(t3);

24 DBMS_OUTPUT.PUT_LINE('Execution Time (secs)');

25 DBMS_OUTPUT.PUT_LINE('---------------------');

26 DBMS_OUTPUT.PUT_LINE('FOR loop: ' || TO_CHAR(t2 - t1));

27 DBMS_OUTPUT.PUT_LINE('FORALL: ' || TO_CHAR(t3 - t2));

28* END;

SQL> /

Execution Time (secs)

---------------------

FOR loop: 38

FORALL: 3

PL/SQL process successfully completed.

In the bulk-bind input collections, you can use the FORALL statement. And in the bulk-bind output collections, you can use the BULK COLLECT clause.

Posted Date: 10/4/2012 3:27:07 AM | Location : United States







Related Discussions:- How bulk bind helps improvement in performance?, Assignment Help, Ask Question on How bulk bind helps improvement in performance?, Get Answer, Expert's Help, How bulk bind helps improvement in performance? Discussions

Write discussion on How bulk bind helps improvement in performance?
Your posts are moderated
Related Questions
PITS Depressions in secondary cell wall is called pit. A pit present on the free cell wall surface without its partner is called Blind pit. It consists of 2 parts -

Dynamic Ranges The PL/SQL lets you determine the loop range dynamically at run time, as the example below shows: SELECT COUNT(empno) INTO emp_count FROM emp; FOR i IN 1..emp_cou

Block Structure The PL/SQL is a block-structured language. That is, the fundamental units (procedures, anonymous blocks, and functions) that make up a PL/SQL program are logi

Datatype Conversion At times it is necessary to convert a value from one datatype to another. For e.g. if you want to inspect a rowid, you should convert it to a character stri

Literature review

Use Serially Reusable Packages To help you to manage the use of memory, the PL/SQL gives the pragma SERIALLY_ REUSABLE that mark some packages as serially reusable . So mark

NULL Statement The NULL statement clearly specifies in action; it does nothing other than to pass control to the next statement. It can, though, improve the readability. In a

Product-specific Packages The Oracle and different Oracle tools are supplied with the product-specific packages which help you to build the PL/SQL-based applications. For illus

Using ROLLBACK The ROLLBACK statements end the present transaction and undo any change made during the transaction. The Rolling back is helpful for two reasons. Firstly, if yo

EXIT The EXIT statement forces a loop to done unconditionally. Whenever an EXIT statement is encountered, the loop is done immediately and controls the passes to the next statem