Faster DML Triggers in Oracle 11g Oracle 11g New Features Tips by Burleson Consulting July 8, 2008

Oracle 11g SQL New Features Tips

Another transparent enhancement with Oracle 11g is quicker triggers, reported to be up to 25% faster when row-level triggers perform DML on other tables.  While this improvement has not been widely publicized by Oracle in the 11g release, it offers a noticeable improvement in several business cases.  For example, this improvement might show substantial benefits in triggers used for auditing. 

To demonstrate the improvement, define a table for sensitive information such as credit_card:

create table
   credit_cards (
   account_id number,
   credit_card_number varchar2(30),
   expiration_date date);

Next, create tables audit_log and audit_tables for storing audit information:

create table
   audit_log (
   username varchar2(30),
   table_name varchar2(30),
   user_operation varchar2(30),
   user_time date); 

create table
   audit_tables (
   table_name varchar2(30),
   last_updated_by varchar2(30),
   last_update_time date);  

Define a trigger on credit_cards that inserts a record into audit_log and updates audit_tables whenever an insert occurs:

CREATE OR REPLACE TRIGGER credit_cards_tr1
BEFORE INSERT
ON VJ.CREDIT_CARDS
REFERENCING NEW AS New OLD AS Old
FOR EACH ROW
DECLARE
BEGIN
   INSERT INTO
      AUDIT_LOG (USERNAME, TABLE_NAME, USER_OPERATION, USER_TIME)
   VALUES
      (USER , 'CREDIT_CARDS', 'INSERT - ' || :NEW.ACCOUNT_ID, SYSDATE );
   UPDATE
      audit_tables
   SET
      last_updated_by = USER,
      last_update_time = SYSDATE
   WHERE
      table_name = 'CREDIT_CARDS';
   EXCEPTION
     WHEN OTHERS THEN
       RAISE;
END credit_cards_tr1;
/

After completing the setup, in Oracle 10.2, the following PL/SQL block should be executed:

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - Production
With the Partitioning, OLAP and Data Mining options 

SQL> set timing on
SQL> DECLARE
  2     i NUMBER := 1;
  3  BEGIN
  4  LOOP
  5  insert into
  6     credit_cards
  7  VALUES (i, '1234123412341234', '01-JAN-2009');
  8  COMMIT;
  9   i := i+1;
 10   EXIT WHEN i>10000;
 11  END LOOP;
 12  END;
 13  /

PL/SQL procedure successfully completed.

Elapsed: 00:00:04.57

Following the same steps on Oracle 11.1, the result is:

Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options 

SQL> set timing on
SQL> DECLARE
  2     i NUMBER := 1;
  3  BEGIN
  4  LOOP
  5  insert into
  6     credit_cards
  7  VALUES (i, '1234123412341234', '01-JAN-2009');
  8  COMMIT;
  9   i := i+1;
 10   EXIT WHEN i>10000;
 11  END LOOP;
 12  END;
 13  / 

PL/SQL procedure successfully completed.

Elapsed: 00:00:04.00

The improvement in trigger execution times appears to be more prevalent as the trigger performs DML on a larger number of tables.  This enhancement should prove to be useful in many situations where triggers perform DML on other tables, such as: 

• Add conclusion

• Make sure statements are more passive

• Make sure headings are correct and sequenced

Through partitioning and index enhancements, Oracle 11g offers many new tools to simplify the tasks of Remote DBAs and developer staffs.

This includes:

• a new partitioning feature, Interval Partitioning to create new partitions

• System partitioning allowing application level control in tables or indexes

• Reference partitioning in Oracle 11g that allows the partitioning of two related tables to be partitioned based on a referential constraint

• Support for partitioning tables using a partitioning key on virtual columns

• New composite partitioning strategies

• Partition pruning utilizing bloom filtering 

To compliment the new partitioning enhancements in Oracle 11g, ILM has also been enhanced allowing easier data movements.

This chapter also includes new index enhancements and features in 11g:

• Invisible indexes useful in many diverse situations

• Extended features of compressed tables for all DML operations

• Improved direct path inserts through directly accessing NFS V3 servers, using an internal Direct NFS Client with the Oracle Database kernel. 

• Another part of the new Oracle 11g enhancements is Database Resident Connection Pooling (DRCP) which supports server-side connection pooling. 

• OCI in 11g then expands use of memory caching to improve query performance. 

• Furthermore, a virtual column, an expression based on existing columns in the table, which in a table can provide advantages in disk space utilization. 

• Additionally, binary XML has been added as a new option for storage. 

Oracle 11g also offers a new feature to improve help requests from Oracle Support called Incident Package Service. Furthermore, enabling read-only tables now utilizes easier processes. 

 

This is an excerpt from the new book Oracle 11g New Features: Expert Guide to the Important New Features by John Garmany, Steve Karam, Lutz Hartmann, V. J. Jain, Brian Carr. You can buy it direct from the publisher for 30% off.