oracle 查看连接数

select * from v$session 

v$session是动态性能表， 是Oracle10gR2新特色

中断会话

ALTER SYSTEM KILL SESSION 'SID,SERIAL#'；

 

 

v$session表每个字段的意义：
$SESSION
This view lists session information for each current session.

Column   Datatype   Description  
SADDR 
RAW(4) 
Session address 

SID 
NUMBER 
Session identifier 

SERIAL# 
NUMBER 
Session serial number. Used to identify uniquely a session's objects. Guarantees that session-level commands are applied to the correct session objects if the session ends and another session begins with the same session ID 

AUDSID 
NUMBER 
Auditing session ID 

PADDR 
RAW(4) 
Address of the process that owns this session 

USER# 
NUMBER 
Oracle user identifier 

USERNAME 
VARCHAR2(30) 
Oracle username 

COMMAND 
NUMBER 
Command in progress (last statement parsed); for a list of values, see Table 3-7 

OWNERID 
NUMBER 
The column contents are invalid if the value is 2147483644. Otherwise, this column contains the identifier of the user who owns the migratable session

For operations using Parallel Slaves, interpret this value as a 4Byte value. The low-order 2Bytes of which represent the session number, and the high-order bytes the instance ID of the query coordinator 

TADDR 
VARCHAR2(8) 
Address of transaction state object 

LOCKWAIT 
VARCHAR2(8) 
Address of lock waiting for; NULL if none 

STATUS 
VARCHAR2(8) 
Status of the session: ACTIVE (currently executing SQL), INACTIVE, KILLED (marked to be killed), CACHED (temporarily cached for use by Oracle*XA), SNIPED (session inactive, waiting on the client) 

SERVER 
VARCHAR2(9) 
Server type: DEDICATED, SHARED, PSEUDO, NONE 

SCHEMA# 
NUMBER 
Schema user identifier 

SCHEMANAME 
VARCHAR2(30) 
Schema user name 

OSUSER 
VARCHAR2(15) 
Operating system client user name 

PROCESS 
VARCHAR2(9) 
Operating system client process ID 

MACHINE 
VARCHAR2(64) 
Operating system machine name 

TERMINAL 
VARCHAR2(10) 
Operating system terminal name 

PROGRAM 
VARCHAR2(48) 
Operating system program name 

TYPE 
VARCHAR2(10) 
Session type 

SQL_ADDRESS 
RAW(4) 
Used with SQL_HASH_VALUE to identify the SQL statement that is currently being executed 

SQL_HASH
_VALUE 
NUMBER 
Used with SQL_ADDRESS to identify the SQL statement that is currently being executed 

MODULE 
VARCHAR2(48) 
Contains the name of the currently executing module as set by calling the DBMS_APPLICATION_INFO.SET_MODULE procedure 

MODULE_HASH 
NUMBER 
The hash value of the above MODULE 

ACTION 
VARCHAR2(32) 
Contains the name of the currently executing action as set by calling the
DBMS_APPLICATION_INFO.SET_ACTION procedure 

ACTION_HASH 
NUMBER 
The hash value of the above action name 

CLIENT_INFO 
VARCHAR2(64) 
Information set by the DBMS_APPLICATION_INFO.SET_CLIENT_INFO procedure 

FIXED_TABLE
_SEQUENCE 
NUMBER 
This contains a number that increases every time the session completes a call to the database and there has been an intervening select from a dynamic performance table. This column can be used by performance monitors to monitor statistics in the database. Each time the performance monitor looks at the database, it only needs to look at sessions that are currently active or have a higher value in this column than the highest value that the performance monitor saw the last time. All the other sessions have been idle since the last time the performance monitor looked at the database 

ROW_WAIT_OBJ# 
NUMBER 
Object ID for the table containing the ROWID specified in ROW_WAIT_ROW# 

ROW_WAIT_FILE# 
NUMBER 
Identifier for the datafile containing the ROWID specified in ROW_WAIT_ROW#. This column is valid only if the session is currently waiting for another transaction to commit and the value of ROW_WAIT_OBJ# is not -1 

ROW_WAIT
_BLOCK# 
NUMBER 
Identifier for the block containing the ROWID specified in ROW_WAIT_ROW#. This column is valid only if the session is currently waiting for another transaction to commit and the value of ROW_WAIT_OBJ# is not -1 

ROW_WAIT_ROW# 
NUMBER 
The current ROWID being locked. This column is valid only if the session is currently waiting for another transaction to commit and the value of ROW_WAIT_OBJ# is not -1 

LOGON_TIME 
DATE 
Time of logon 

LAST_CALL_ET 
NUMBER 
The last call 

PDML_STATUS 
VARCHAR2(8) 
If ENABLED, the session is in a PARALLEL DML enabled mode. If DISABLED, PARALLEL DML enabled mode is not supported for the session. If FORCED, the session has been altered to force PARALLEL DML. 

PDDL_STATUS 
VARCHAR2(8) 
If ENABLED, the session is in a PARALLEL DDL enabled mode. If DISABLED, PARALLEL DDL enabled mode is not supported for the session. If FORCED, the session has been altered to force PARALLEL DDL. 

PDML_ENABLED 
VARCHAR2(3) 
This column has been replaced by PDML_ENABLED and PDML_STATUS. See above. 

FAILOVER_TYPE 
VARCHAR2(10) 
NONE if failover is disabled for this session, SESSION if client is able to failover its session following a disconnect, and SELECT if client is able to fail over selects in progress as well 

FAILOVER
_METHOD 
VARCHAR2(3) 
NONE if failover is disabled for this session, BASIC if client reconnects following a disconnect, PRECONNECT if the backup instance is able to support all connections from every instance that it is backup for 

FAILED_OVER 
VARCHAR2(13) 
TRUE if running in failover mode and have failed over, otherwise FALSE 

RESOURCE_CONSUMER_GROUP 
VARCHAR2(32) 
Name of the session's current resource consumer group

为了更有效的保留Session信息，Oracle10g新增加了一个v$session_wait_history视图
该视图用以记录活动Session的最近10次等待事件。

 

SQL> select event,p1text,p1,p2text,p2,p3text,p3,wait_time
  2  from v$session_wait_history where sid=120;

EVENT                         P1TEXT         P1 P2TEXT                 P2 P3TEXT   P3  WAIT_TIME
---------------------------- -------- -------- --------------- ---------- -------- -- ----------
db file sequential read      file#          14 block#               97456 blocks    1          0
row cache lock            cache id          11 mode                     0 request   3         49
row cache lock            cache id          11 mode                     0 request   3          0
db file sequential read      file#          10 block#              260171 blocks    1          1
db file sequential read      file#          14 block#              570536 blocks    1         10
db file sequential read      file#          14 block#                6363 blocks    1         12
db file sequential read      file#          14 block#               35285 blocks    1          9
db file sequential read      file#          14 block#               40674 blocks    1          9
db file sequential read      file#          14 block#               69631 blocks    1          1
db file sequential read      file#          14 block#               82498 blocks    1          3

10 rows selected