How to update cursor limit for ORA-01000: maximum open cursors exceed

Question

I have found my max number of cursors per database to be 300 from the following query:

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;

I tried to update the amount to 1000 with this:

  update v_$parameter
  set value = 1000
  where name = 'open_cursors';

But I am seeing this error:

SQL Error: ORA-02030: can only select from fixed tables/views
02030. 00000 -  "can only select from fixed tables/views"
*Cause:    An attempt is being made to perform an operation other than
           a retrieval from a fixed table/view.
*Action:   You may only select rows from fixed tables/views.

What is the proper way to update the open_cursor value? Thanks.

Answer 1

Assuming that you are using a spfile to start the database

alter system set open_cursors = 1000 scope=both;

If you are using a pfile instead, you can change the setting for the running instance

alter system set open_cursors = 1000 

You would also then need to edit the parameter file to specify the new open_cursors setting. It would generally be a good idea to restart the database shortly thereafter to make sure that the parameter file change works as expected (it's highly annoying to discover months later the next time that you reboot the database that some parameter file change than no one remembers wasn't done correctly).

I'm also hoping that you are certain that you actually need more than 300 open cursors per session. A large fraction of the time, people that are adjusting this setting actually have a cursor leak and they are simply trying to paper over the bug rather than addressing the root cause.

Answer 2

RUn the following query to find if you are running spfile or not:

SELECT DECODE(value, NULL, 'PFILE', 'SPFILE') "Init File Type" 
       FROM sys.v_$parameter WHERE name = 'spfile';

If the result is "SPFILE", then use the following command:

alter system set open_cursors = 4000 scope=both; --4000 is the number of open cursor

if the result is "PFILE", then use the following command:

alter system set open_cursors = 1000 ;

You can read about SPFILE vs PFILE here,

http://www.orafaq.com/node/5