Oracle dblink造成远程数据库session过多

当场报网企业数据库查询连不上，先查验了下数据库查询processes=1500,session=2200.我认为挺大啊，这一数据库查询沒有好多个在用。

查询v$session中的session数最多是哪家machine进行的，发觉是省企业的数据库查询进行的session，找开发设计整理了下业务流程，省企业同歩dblink实际操作网企业表，且是根据weblogic的连接池。

哦，有点儿懂了，是dblink造成的，weblogic连接池是始终存有的，因此在网企业端session不是释放出来的，要是省企业把运用都停用，那在网企业端的session都是释放出来。要认证念头，做个实验：

总体目标：数据库查询A上建dblink,改动数据库查询B上的表。

自然环境提前准备：

1.在数据库查询A上建dblink

create public database link TO_B

connect to TEST_DB identified by  TEST_DB

using '(DESCRIPTION =(ADDRESS_LIST =(ADDRESS = (PROTOCOL = TCP)(HOST = 10.10.15.150)(PORT = 1521)))(CONNECT_DATA =(SID = orcl)))';

2.在数据库查询B上建表

create table TEST(  ID NUMBER );

insert into test values(1);

刚开始检测：

1.在数据库查询B上select count(1) from v$session;

2.在数据库查询A上update test@TO_B set id=1;

commit;

3.在数据库查询B上select count(1) from v$session; 可以看涨了1个

比照检测：

1.在数据库查询B上select count(1) from v$session;

2.在数据库查询A上update test@TO_B set id=1;

commit;

alter session close database link TO_B;

3.在数据库查询B上select count(1) from v$session; 可以看沒有转变

小结： 出現这类难题，说到底是实际操作dblink不标准，用了以后沒有关掉。

附录为官方网文本文档：

32 Managing a Distributed DatabaseClosing Database Links

If you access a database link in a session, then the link remains open until you close the session. A link is open in the sense that a process is active on each of the remote databases accessed through the link. This situation has the following consequences:

If 20 users open sessions and access the same public link in a local database, then 20 database link connections are open.

If 20 users open sessions and each user accesses a private link, then 20 database link connections are open.

If one user starts a session and accesses 20 different links, then 20 database link connections are open.

After you close a session, the links that were active in the session are automatically closed. You may have occasion to close the link manually. For example, close links when:

The network connection established by a link is used infrequently in an application.

The user session must be terminated.

To close a link, issue the following statement, where linkn