查看oracle數據庫的連接數和用戶

http://www.cnblogs.com/is1988/archive/2012/11/21/2780067.html

一、查詢oracle的鏈接數
select count(*) from v$session;
二、查詢oracle的併發鏈接數
select count(*) from v$session where status='ACTIVE';
三、查看不一樣用戶的鏈接數
select username,count(username) from v$session where username is not null group by username;
四、查看全部用戶：
select * from all_users;
五、查看用戶或角色系統權限(直接賦值給用戶或角色的系統權限)：
select * from dba_sys_privs;
select * from user_sys_privs;
六、查看角色(只能查看登錄用戶擁有的角色)所包含的權限
select * from role_sys_privs;
七、查看用戶對象權限：
select * from dba_tab_privs;
select * from all_tab_privs;
select * from user_tab_privs;
八、查看全部角色：
select * from dba_roles;
九、查看用戶或角色所擁有的角色：
select * from dba_role_privs;
select * from user_role_privs;
十、查看哪些用戶有sysdba或sysoper系統權限(查詢時須要相應權限)
select * from V$PWFILE_USERS;

select count(*) from v$process --當前的鏈接數
select value from v$parameter where name = 'processes' --數據庫容許的最大鏈接數
修改最大鏈接數:
alter system set processes = 300 scope = spfile;

重啓數據庫:
shutdown immediate;
startup;

--查看當前有哪些用戶正在使用數據
SELECT osuser, a.username,cpu_time/executions/1000000||'s', sql_fulltext,machine
from v$session a, v$sqlarea b
where a.sql_address =b.address order by cpu_time/executions desc;
select count(*) from v$session #鏈接數

select count(*) from v$session where status='ACTIVE'　#併發鏈接數

show parameter processes #最大鏈接

alter system set processes = value scope = spfile;重啓數據庫 #修改鏈接

 

SQL> Select count(*) from v$session where status='ACTIVE' ;

COUNT(*)
----------
20

SQL> Select count(*) from v$session;

COUNT(*)
----------
187

SQL> show parameter processes;

NAME TYPE VALUE
------------------------------------ ----------- ----------
aq_tm_processes integer 0
db_writer_processes integer 1
gcs_server_processes integer 0
job_queue_processes integer 10
log_archive_max_processes integer 2
processes integer 450
SQL>

併發指active,I SEE

SQL> select count(*) from v$session #鏈接數
SQL> Select count(*) from v$session where status='ACTIVE'　#併發鏈接數
SQL> show parameter processes #最大鏈接
SQL> alter system set processes = value scope = spfile;重啓數據庫 #修改鏈接

unix 1個用戶session 對應一個操做系統 process
而 windows體如今線程

DBA要定時對數據庫的鏈接狀況進行檢查，看與數據庫創建的會話數目是否是正常，若是創建了過多的鏈接，會消耗數據庫的資源。同時，對一些「掛死」的鏈接，可能會須要DBA手工進行清理。
如下的SQL語句列出當前數據庫創建的會話狀況:
select sid,serial#,username,program,machine,status
from v$session;
輸出結果爲:
SID SERIAL# USERNAME PROGRAM MACHINE STATUS
---- ------- ---------- ----------- --------------- --------
1 1 ORACLE.EXE WORK3 ACTIVE
2 1 ORACLE.EXE WORK3 ACTIVE
3 1 ORACLE.EXE WORK3 ACTIVE
4 1 ORACLE.EXE WORK3 ACTIVE
5 3 ORACLE.EXE WORK3 ACTIVE
6 1 ORACLE.EXE WORK3 ACTIVE
7 1 ORACLE.EXE WORK3 ACTIVE
8 27 SYS SQLPLUS.EXE WORKGROUP\\WORK3 ACTIVE
11 5 DBSNMP dbsnmp.exe WORKGROUP\\WORK3 INACTIVE
其中，
SID 會話(session)的ID號;
SERIAL# 會話的序列號，和SID一塊兒用來惟一標識一個會話;
USERNAME 創建該會話的用戶名;
PROGRAM 這個會話是用什麼工具鏈接到數據庫的;
STATUS 當前這個會話的狀態，ACTIVE表示會話正在執行某些任務，INACTIVE表示當前會話沒有執行任何操做;
若是DBA要手工斷開某個會話，則執行:
alter system kill session \'SID,SERIAL#\'

sql語句
SQL語句以下：

SELECT username, machine, program, status, COUNT (machine) AS
鏈接數量
FROM v$session
GROUP BY username, machine, program, status
ORDER BY machine;

顯示結果（每一個人的機器上會不一樣）

SCHNEIDER|WORKGROUD\WANGZHENG|TOAD.exe|ACTIVE|1SCHNEIDER|WORKGROUP\597728AA514F49D|sqlplusw.exe|INACTIVE|1|WWW-Q6ZMR2OIU9V|ORACLE.EXE|ACTIVE|8PUBLIC|||INACTIVE|0 按主機名查詢SELECT COUNT(*) FROM V$SESSION WHERE MACHINE = 'DXMH'; 'DXMH'爲主機名 數據恢復語句create table informationlaw_bak as select * from informationlaw as of TIMESTAMP to_timestamp('20121126 103435','yyyymmdd hh24miss'); //按機器名分組查select username,machine,count(username) from v$session where username is not null group by username,machine;