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Recently I received errors messages from OEM13c saying too many cursors were opened in a database:

instance_throughput:ORA-01000: maximum open cursors exceeded

My database had currently this open_cursors value:

SQL> show parameter open_cursors

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
open_cursors                         integer     300

I decided to increase its value to 800:

SQL> alter system set open_cursors=800;

System altered.

But a few minutes later I received again the same message. I decided to have a more precise look to discover what’s was happening.

SQL> SELECT  max(a.value) as highest_open_cur, p.value as max_open_cur FROM v$sesstat a, v$statname b, v$parameter p WHERE  a.statistic# = b.statistic#  and b.name = 'opened cursors current' and p.name= 'open_cursors' group by p.value;

HIGHEST_OPEN_CUR     MAX_OPEN_CUR
   300                 800

So I need to  find out which session is causing the error:

SQL> select a.value, s.username, s.sid, s.serial# from v$sesstat a, v$statname b, v$session s where a.statistic# = b.statistic#  and s.sid=a.sid and b.name = 'opened cursors current' and s.username is not null;

     VALUE USERNAME                              SID    SERIAL#
---------- ------------------------------ ---------- ----------
         9 SYS                                     6      36943
         1 SYS                                   108      31137
         1 SYS                                   312      15397
       300 SYS                                   417      31049
        11 SYS                                   519      18527
         7 SYS                                   619      48609
         1 SYS                                   721      51139
         0 PUBLIC                                922         37
        17 SYS                                  1024          1
        14 SYS                                  1027      25319
         1 SYS                                  1129      40925

A sys connection is using 300 cursors :=(( let’s see what it is:

Great the agent 13c is causing the problem :=((

I already encountered this kind of problem on another client’s site. In fact the agent 13c is using metrics to determine the High Availability Disk or Media Backup every 15 minutes and is using a lot of cursors. The best way is to disable those metrics to avoid ORA-01000 errors:

After reloading the agent and reevaluating the alert, the incident disappeared successfully :=)

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Pierre Sicot
Pierre Sicot

Senior Consultant