How to Find Maximum Open Cursors and Current Cursor Count in Oracle Database
Need to monitor and manage Oracle database cursors? This guide shows you how to check maximum allowed cursors and track currently open cursors to prevent the dreaded ORA-01000 error.
Understanding Oracle Cursors
Before diving into the queries, let’s understand what cursors are and why monitoring them is crucial for database performance.
What is a Cursor?
In Oracle, a cursor is a memory area that holds the context of a SQL statement execution. Every SQL statement requires a cursor, and Oracle has a limit on how many can be open simultaneously.
Checking Maximum Open Cursors
To find out the maximum number of cursors allowed per session:
SELECT name, value
FROM v$parameter
WHERE name = 'open_cursors';
Monitoring Current Open Cursors
To check how many cursors are currently open in your session:
SELECT a.value, s.username, s.machine
FROM v$sesstat a, v$statname b, v$session s
WHERE a.statistic# = b.statistic#
AND s.sid = a.sid
AND b.name = 'opened cursors current';
Finding Cursor Usage by Session
To get a detailed view of cursor usage by session:
SELECT ss.username,
ss.machine,
se.value "Current Cursors"
FROM v$sesstat se,
v$statname sn,
v$session ss
WHERE se.statistic# = sn.statistic#
AND ss.sid = se.sid
AND sn.name = 'opened cursors current'
AND ss.username IS NOT NULL
ORDER BY se.value DESC;
Best Practices for Cursor Management
- Monitor Regularly: Check cursor usage periodically
- Set Appropriate Limits: Configure open_cursors based on application needs
- Close Cursors: Ensure applications properly close cursors
- Use Cursor Sharing: Enable cursor sharing when appropriate
Troubleshooting ORA-01000 Errors
If you encounter the ORA-01000 “maximum open cursors exceeded” error:
- Check current cursor usage
- Identify sessions with high cursor counts
- Review application code for cursor leaks
- Consider increasing open_cursors parameter
Related Oracle Parameters
Other important parameters affecting cursor behavior:
SELECT name, value
FROM v$parameter
WHERE name IN (
'session_cached_cursors',
'cursor_sharing',
'open_cursors'
);
Resources
This article is part of our Oracle Database Administration series. Check out our other database optimization tutorials.