Performance Issue with sql query

Question

Hi,
My db is 10.2.0.5 with RAC on ASM, Cluster ware version 10.2.0.5.
With bsoa table as
SQL> desc bsoa;
Name                                      Null?    Type
ID                                        NOT NULL NUMBER
LOGIN_TIME                                         DATE
LOGOUT_TIME                                        DATE
SUCCESSFUL_IND                                     VARCHAR2(1)
WORK_STATION_NAME                                  VARCHAR2(80)
OS_USER                                            VARCHAR2(30)
USER_NAME                                 NOT NULL VARCHAR2(30)
FORM_ID                                            NUMBER
AUDIT_TRAIL_NO                                     NUMBER
CREATED_BY                                         VARCHAR2(30)
CREATION_DATE                                      DATE
LAST_UPDATED_BY                                    VARCHAR2(30)
LAST_UPDATE_DATE                                   DATE
SITE_NO                                            NUMBER
SESSION_ID                                         NUMBER(8)
The query
UPDATE BSOA SET LOGOUT_TIME =SYSDATE WHERE SYS_CONTEXT('USERENV', 'SESSIONID') = SESSION_ID
Is taking a lot of time to execute and in AWR reports also it is on top in
1. SQL Order by elapsed time
2. SQL order by reads
3. SQL order by gets
So i am trying a way to solve the performance issue as the application is slow specially during login and logout time.
I understand that the function in the where condition cause to do FTS, but i can not think what other parts to look at.
Also:
SQL> SELECT COUNT(1) FROM BSOA;
  COUNT(1)
   7800373
The explain plan for  "UPDATE BSOA SET LOGOUT_TIME =SYSDATE WHERE SYS_CONTEXT('USERENV', 'SESSIONID') = SESSION_ID" is
{code}
PLAN_TABLE_OUTPUT
Plan hash value: 1184960901
| Id  | Operation          | Name               | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | UPDATE STATEMENT   |                    |     1 |    26 | 18748   (3)| 00:03:45 |
|   1 |  UPDATE            | BSOA |       |       |            |          |
|*  2 |   TABLE ACCESS FULL| BSOA |     1 |    26 | 18748   (3)| 00:03:45 |
Predicate Information (identified by operation id):
   2 - filter("SESSION_ID"=TO_NUMBER(SYS_CONTEXT('USERENV','SESSIONID')))
{code}

Answer 1

Hi,
There are also triggers before update and AUDITS on this table.
CREATE OR REPLACE TRIGGER B2.TRIGGER1
BEFORE UPDATE
ON B2.BSOA  REFERENCING OLD AS OLD NEW AS NEW
FOR EACH ROW
:NEW.LAST_UPDATED_BY   := USER    ;
:NEW.LAST_UPDATE_DATE  := SYSDATE ;
END;
CREATE OR REPLACE TRIGGER B2.TRIGGER2
BEFORE INSERT
ON B2.BSOA  REFERENCING OLD AS OLD NEW AS NEW
FOR EACH ROW
:NEW.CREATED_BY        := USER ;
:NEW.CREATION_DATE     := SYSDATE ;
:NEW.LAST_UPDATED_BY   := USER    ;
:NEW.LAST_UPDATE_DATE  := SYSDATE ;
END;
And also there is an audit on this table
AUDIT UPDATE ON B2.BSOA BY ACCESS WHENEVER SUCCESSFUL;
AUDIT UPDATE ON B2.BSOA BY ACCESS WHENEVER NOT SUCCESSFUL;
And the sessionid column in BSOA has height balanced histogram.
When i create an index i get the following error. As i am on 10g I can't use DDL_LOCK_TIMEOUT . I may have to wait for next down time.
SQL> CREATE INDEX B2.BSOA_SESSID_I ON B2.BSOA(SESSION_ID) TABLESPACE B2 COMPUTE STATISTICS;
CREATE INDEX B2.BSOA_SESSID_I ON B2.BSOA(SESSION_ID) TABLESPACE B2 COMPUTE STATISTICS
ERROR at line 1:
ORA-00054: resource busy and acquire with NOWAIT specified
Thanks