?可以用如下命令查看數據庫連接的消耗情況

select  b.MACHINE, b.PROGRAM, b.USERNAME, count(*) from v$process a, v$session b where a.ADDR = b.PADDR and  b.USERNAME is not null   
group by  b.MACHINE, b.PROGRAM, b.USERNAME order by count(*) desc

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在 oracle中，要經常查看process:
查看ORACLE最大進程數：
SQL> select count(*) from v$session  #連接數
SQL> Select count(*) from v$session where status='ACTIVE'　#并發連接數
SQL> show parameter processes  #最大連接
SQL> alter system set processes = value scope = spfile;重啟數據庫  #修改連接
unix 1個用戶session 對應一個操作系統 process
而 windows體現在線程
------------------------------------------------------------------------------
修改ORACLE最大進程數：
使用sys，以sysdba權限登錄：
SQL> show parameter processes;
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     1
db_writer_processes                  integer     1
job_queue_processes                  integer     10
log_archive_max_processes            integer     1
processes                            integer     150
SQL> alter system set processes=300 scope = spfile;
系統已更改。
SQL> show parameter processes;
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     1
db_writer_processes                  integer     1
job_queue_processes                  integer     10
log_archive_max_processes            integer     1
processes                            integer     150
SQL> create pfile from spfile;
文件已創建。
重啟數據庫，SQL> show parameter processes;
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     1
db_writer_processes                  integer     1
job_queue_processes                  integer     10
log_archive_max_processes            integer     1
processes                            integer     300
還有可以查詢select sessions_highwater  from v$license;sessions_highwater 記錄的是數據庫會話曾經達到的最大值查詢數據庫自啟動以來最大的并發數量select * from v$license

?-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;

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