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HomeDatabaseMysql Tutorial关于ORA-01000: maximum open cursors exceeded" 问题分析总结

关于ORA-01000: maximum open cursors exceeded 问题分析总结

关于ora-01000:超出最大可打开的游标数 的一点理解
 ORA-01000: maximum open cursors exceeded"怎么解决
 ERROR at line 1:
 ORA-01000: maximum open cursors exceeded

问题分析:
 1.游标open后,出错了又没有close.
 2.可能是表结构的问题。
 
解决方法:
 step 1:
    查看数据库当前的游标数配置
    show parameter open_cursors;
 

step 2:
    查看游标使用情况:
 select o.sid, oSUSEr, machine, count(*) num_curs
 from v$open_cursor o, v$session s
 where user_name = 'user' and o.sid=s.sid
 group by o.sid, osuser, machine
 order by  num_curs desc;
 
此处的user_name='user'中,user代表占用数据库资源的数据库用户名.
 

step 3:
    查看游标执行的sql情况:
 select o.sid q.sql_text
 from v$open_cursor o, v$sql q
 where q.hash_value=o.hash_value and o.sid = 123;
 
step 4:
    根据游标占用情况分析访问数据库的程序在资源释放上是否正常,如果程序释放资源没有问题,则加大游标数。
    alter system set open_cursors=2000 scope=both;
   
 以上为cursors数确实不够的情况下的处理方法。
 但在有的时候,就算是加大了open_cursor 。譬如,我将游标大小改到了300,还是出现错误,改到1000以后开始出现了ORA-01001:invalid cursors。再怎么加大
 open_cursors的数量都无济于事。碰到这种情况极可能就是表结构的问题了。
 

 

那么如何来验证呢?
 案例来自itpub,yangtingkun:
 “我们系统的数据量比较大,近200张表,有些表一天要插入1000000条左右的数据。表是使用ER/STDIO设计的,然后直接生成建表的脚本,,由于没有设置physical_attributes_clause语句中的建表参数,因此使用了默认的参数。好像是INITIAL 10K NEXT 10K PCTFREE 20 PCTUSED 50由于表的存储空间太小,在
 很短的时间内就会装满,因此Oracle就需要不停为30多张表(数据量较大的)申请空间。于是在程序运行了一段时间后,开始出现ORA-01000: maximum open
 cursors exceeded的错误。 我将游标大小改到了300,还是出现错误,改到1000以后开始出现了ORA-01001:invalid cursors。再怎么加大open_cursors的数量都
 无济于事。 使用select * from v$open_cursors查询,发现有几百条的INSERT语句游标没有释放。
 
开始怀疑是程序调用的问题,仔细检查程序没有发现问题。但是发现对某张表进行TRUNCATE操作后,对此表进行插入的游标全部释放,于是开始怀疑是表结构本
 身的问题。重新设置了建表参数,将数据量最大的表的INITIAL和NEXT均设置为50M。至今未再出现同样的错误。”
 

FYI:
 首先通过v$open_cursor中的SQL_TEXT字段可以查出没有释放的SQL是大致是什么语句。
 由于建表参数设置不当,会有很多的INSERT语句无法释放。
 

 

SELECT * FROM V$OPEN_CURSOR WHERE SQL_TEXT LIKE 'INSERT%‘
 
找一找哪些表的INSERT语句没有释放的游标比较多。从ALL_TABLES里查看该表的建表参数是否合适。
 

yangtingkun的分析:
 “开始时表参数
 PCT FREE 10
 PCT USED 40
 STORAGE(INITIAL 10K
        NEXT 10K
        MINEXTENTS 1
        MAXEXTENTS 121
        PCTINCREASE 0
        )
 9K的空间,以我们的系统几秒钟就塞满了,下一条插入语句来的时候ORACLE要去自动申请空间,该语句所占用的游标暂时无法释放。ORACLE申请的空间马上又被
 塞满,又要去申请新的空间。如果二、三十多张表在几个钟头内都不停要求ORACLE去进行上述的操作,估计会造成大量的游标来不及释放。以上只是我的估计。”

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