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
DELETE Statement The DELETE statement eliminates whole rows of data from the specified table or view. Syntax:

Advantages of Wrapping   The PL/SQL Wrapper convert the PL/SQL source code into a transitional form of the object code. By hiding the application internals, the Wrapper secure

Forward Declarations The PL/SQL needs that you declare an identifier before using it. And hence, you should declare a subprogram before calling it. For illustration, the decla

Scoping Within the similar scope, all the declared identifiers should be unique. So, even if their datatypes differ, the variables and parameters cannot share the similar name.

Rephrase Conditional Control Statements When computing a logical expression, the PL/SQL uses short-circuit evaluation. That is, the PL/SQL stops evaluating the expression as s

Updating Variables For assignment, SQL uses the key word SET, as in SET X = X + 1 (read as "set X equal to X+1") rather than X: = X + 1 as found in many computer languages.

Example of Null operator - NiNo Rule If we wanted to make HIGHER_OF adhere to "NULL in, NULL out"-let's call it the NiNo rule-we would have to write something like what is sho

MERGE and TRUNCATE in SQL SQL has two more table update operators, MERGE and TRUNCATE. MERGE, like INSERT, takes a source table s and uses it to update a target table t. Brief

Implicit Rollbacks Before execute the INSERT, UPDATE, or DELETE statement, the Oracle marks an implicit savepoint . When the statement fails, the Oracle rolls back to the save

Using %ROWTYPE The %ROWTYPE attribute gives a record type which represents a row in a table (or view). The record can store the whole row of data selected from the table or fetc