List all open oracle cursors by user or username

SQL Code

 1set pages 999 lines 300
 2col username format a40
 3select 	sess.username as username
 4,	sess.sid as sid
 5,	sess.serial# as serial
 6,	stat.value cursors
 7from	v$sesstat stat
 8,	v$statname sn
 9,	v$session sess
10where	sess.username is not null
11and	sess.sid = stat.sid
12and	stat.statistic# = sn.statistic#
13and	sn.name = 'opened cursors current'
14order by value
15/

Sample Oracle Output:

 1USERNAME               SID    SERIAL#    CURSORS
 2--------------- ---------- ---------- ----------
 3SYS                    143         10          1
 4WEBUSER                132      33364          3
 5WEBUSER                116      18996          3
 6WEBUSER                118      23832          3
 7WEBUSER                120        423          3
 8ORA_TIV                126      37072          3
 9WEBUSER                127       4392          3
10WEBUSER                124      20787          4
11SYS                    131      34710          5
12CNUSERMAN              145      19887          5
13CNUSERMAN              129       8407          5
14CNUSERMAN              144      17898          5
15CNUSERMAN              141       3881          5
16ORA_TIV                139       5349          8
17ORA_TIV                115       6676          9
18
1915 rows selected.
20SQL>

Purpose:

• To identify and display information about user sessions that have opened a significant number of cursors, which can potentially impact database performance and resource utilization.

Breakdown:

Formatting Output:

*   `set pages 999 lines 300`: Adjusts display settings to accommodate potentially large results.
*   `col username format a40`: Formats the `username` column for readability.

Querying Session and Cursor Data:

*   **Joining Views:** Combines information from multiple database views:
    
    *   `v$sesstat`: Contains session-level statistics, including cursor usage.
    *   `v$statname`: Stores names and descriptions of statistics.
    *   `v$session`: Provides details about active user sessions.
    
*   **Filtering Criteria:**
    
    *   `where sess.username is not null`: Includes only sessions with known usernames.
    *   `and sess.sid = stat.sid`: Matches session IDs to ensure accurate cursor data.
    *   `and stat.statistic# = sn.statistic#`: Links statistics to their names.
    *   `and sn.name = 'opened cursors current'`: Focuses on the specific statistic for opened cursors.
    
*   **Selecting Relevant Information:**
    
    *   `select sess.username, sess.sid, sess.serial#, stat.value cursors`: Retrieves username, session ID, serial number, and cursor count for each matching session.
    
*   **Ordering Results:**
    
    *   `order by value`: Presents results in descending order of cursor count, highlighting sessions with the most open cursors.

Key Points:

• Cursor Focus: Specifically targets the 'opened cursors current' statistic, indicating actively open cursors.
• Session Identification: Provides details about sessions with high cursor usage, aiding in troubleshooting and optimization.
• User-Centric View: Presents information in a user-friendly format, allowing for easy identification of sessions contributing to potential cursor issues.

Insights and Explanations:

• Cursor Management: Oracle uses cursors to manage SQL statement execution. Excessive open cursors can consume memory and resources, potentially impacting performance.

• Troubleshooting:

  • High cursor counts can signal inefficient application code, unclosed cursors, or database configuration issues.
  • Identifying sessions with high cursor usage directs attention to potential problem areas.

• Optimization:

  • Reviewing application code for proper cursor handling can help prevent excessive opening.
  • Adjusting database parameters related to cursor management may be necessary in some cases.

• Monitoring:

  • Regularly monitoring cursor usage can proactively identify and address issues before they impact performance significantly.