Oraclewaitevent wait event

The concept of wait events is introduced from ORACLE7.0.12, with approximately 100 wait events. In ORACLE8.0, this number is increased to about 150. in ORACLE8I

The concept of wait events is introduced from ORACLE 7.0.12, with roughly 100 wait events. In ORACLE 8.0, this number is increased to about 150. in ORACLE 8I

Wait for the event source to start
The concept of wait events is introduced from Oracle 7.0.12, with roughly 100 wait events. In ORACLE 8.0, this number has increased to about 150, with about 220 events in ORACLE 8I and about 400 waiting events in ORACLE 9IR2. in ORACLE 10GR2, there are about 874 waiting events.

Although different versions and component events, '% B0 % B2 % D7 % b0'); "target =" _ self "> the installation may have different waiting events, however, these wait events can be obtained by querying the V $ EVENT_NAME View:

SQL> select * from v $ version;

BANNER

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

Oracle Database 10g Enterprise Edition Release 10.2.0.1.0-Prod

PL/SQL Release 10.2.0.1.0-Production

CORE 10.2.0.1.0 Production

TNS for 32-bit Windows: Version 10.2.0.1.0-Production

NLSRTL Version 10.2.0.1.0-Production

SQL> select count (*) from v $ event_name;

COUNT (*)

----------

872

ORACLE wait events can be divided into two types, namely IDLE (IDLE) Wait events and non-IDLE (NON-IDLE) Wait events.

1). idle waiting events refer to events that ORACLE is waiting for a job. When diagnosing and optimizing databases, you don't need to pay too much attention to these events.

2) Non-idle wait events are specific to ORACLE activities, which refer to the waiting events that occur during database tasks or application running. These waiting events need to be paid attention to and researched when adjusting the database.

Let's take a look at the main categories of ORACLE 10GR2 and the number of various types of wait events:

SQL> select wait_class #, wait_class_id, wait_class, count (*) as "count"

2 from v $ event_name

3 group by wait_class #, wait_class_id, wait_class

4 order by wait_class #;

WAIT_CLASS # WAIT_CLASS_ID WAIT_CLASS count

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

0 1893977003 Other 588

1 4217450380 Application 12

2 3290255840 Configuration 23

3 4166625743 Administrative 46

4 3875070507 Concurrency 24

5 3386400367 Commit 1

6 2723168908 Idle 62

7 2000153315 Network 26

8 1740759767 User I/O 17

9 4108307767 System I/O 24

10 2396326234 Scheduler 2

11 3871361733 Cluster 47

12 rows selected.

Common idle events include:

• Dispatcher timer

• Lock element cleanup

• Null event

• Parallel query dequeue wait

• Parallel query idle wait-Slaves

• Pipe get

• PL/SQL lock timer

• Pmon timer-pmon

• Rdbms ipc message

• Slave wait

• Smon timer

• SQL * Net break/reset to client

• SQL * Net message from client

• SQL * Net message to client

• SQL * Net more data to client

• Virtual circuit status

• Client message

Some common non-idle wait events include:

• Db file scattered read

• Db file sequential read

• Buffer busy waits

• Free buffer waits

• Enqueue

• Latch free

• Log file parallel write

• Log file sync