How to check high CPU utilization in Oracle database?

Oracle database is known for its high performance and scalability, but at times, it can encounter issues such as high CPU utilization. High CPU utilization can lead to slow query responses, decreased overall performance, and an inefficient use of computing resources. In this article, we will explore various methods to identify and check high CPU utilization in an Oracle database.

Why is High CPU Utilization a Concern?

CPU (Central Processing Unit) is a critical resource that carries out all the processing tasks within a computer system, including running the Oracle database. High CPU utilization indicates that the CPU is working at or close to its maximum capacity, which can cause performance degradation and impact the user experience. By identifying and addressing high CPU utilization, you can optimize the database’s performance and ensure efficient resource allocation.

How to Check High CPU Utilization in Oracle Database?

To check high CPU utilization in Oracle database, follow these steps:

1. Use Oracle Enterprise Manager (OEM): Oracle Enterprise Manager provides a graphical interface to monitor database performance. Navigate to the Database menu, select Monitoring, and then click the Performance tab to view CPU utilization metrics.

2. Query the V$SYSMETRIC view: Execute the following query to retrieve CPU utilization information: “SELECT * FROM V$SYSMETRIC WHERE METRIC_NAME = ‘CPU Usage Per Sec'”.

3. Use STATSPACK: STATSPACK is a performance diagnostic tool provided by Oracle. Install and configure STATSPACK, and then generate a STATSPACK report to analyze CPU utilization.

4. Query the V$SYSSTAT view: Execute the following query to obtain cumulative CPU usage statistics: “SELECT (CPU_USED/100) || ‘%’ AS CPU_Utilization FROM V$SYSSTAT WHERE NAME = ‘CPU used by this session'”.

5. Check AWR reports: AWR (Automatic Workload Repository) collects performance data periodically, providing a wealth of information, including CPU utilization. Generate an AWR report and investigate the CPU-related sections.

6. Use Oracle SQL Developer: Oracle SQL Developer offers a comprehensive set of performance monitoring and diagnostic tools. Launch SQL Developer, navigate to Reports, and select the Performance tab to examine CPU utilization.

7. Query the V$OSSTAT view: Execute the following query to gather operating system statistics, including CPU utilization: “SELECT * FROM V$OSSTAT WHERE STAT_NAME LIKE ‘%CPU%'”.

8. Check the output of the TOP command: In Unix or Linux environments, use the TOP command to view real-time CPU utilization. Look for the Oracle database processes consuming excessive CPU.

9. Use the Oracle Cloud Infrastructure (OCI) Console: If your Oracle database is running on Oracle Cloud Infrastructure, navigate to the OCI Console, select the database instance, and examine the CPU utilization graph under Metrics.

10. Query the V$PROCESS view: Execute the following query to determine CPU utilization for each active process in Oracle: “SELECT PID, USERNAME, CPU_TIME FROM V$PROCESS ORDER BY CPU_TIME DESC”.

11. Use Oracle Active Session History (ASH): ASH records detailed information about active sessions in the database. Analyze ASH data to identify sessions with high CPU consumption.

12. Monitor wait events: Excessive CPU consumption might be caused by wait events. Monitor the V$SYSTEM_EVENT view to identify any significant waits related to CPU usage.

Frequently Asked Questions (FAQs)

1. How can I reduce high CPU utilization in an Oracle database?

To reduce high CPU utilization, you can optimize SQL queries, ensure proper indexing, allocate more resources, tune the database configuration, and consider upgrading hardware if necessary.

2. Can multiple queries running simultaneously cause high CPU utilization?

Yes, running multiple resource-intensive queries simultaneously can increase CPU utilization. Monitor and manage concurrent execution to avoid resource contention.

3. Does high CPU utilization always indicate a problem?

Not necessarily. High CPU utilization can be expected during peak workloads. However, sustained high CPU utilization outside peak times might indicate a performance issue.

4. How can poorly written SQL statements impact CPU utilization?

Poorly written SQL statements can result in suboptimal execution plans, leading to excessive CPU consumption. Proper query optimization can mitigate this issue.

5. What impact does CPU utilization have on other resources in the database?

High CPU utilization can cause resource contention and impact memory, disk I/O, and network utilization, leading to degraded overall performance.

6. Can insufficient memory cause high CPU utilization?

Yes, insufficient memory can cause excessive disk I/O, which, in turn, can increase CPU utilization. Allocate enough memory to accommodate the database workload.

7. How can I check CPU utilization for a specific Oracle session?

You can query the V$SESSION view and retrieve the CPU_TIME column to determine the CPU utilization for a specific Oracle session.

8. Is it possible to limit CPU utilization per Oracle session?

Oracle Resource Manager enables you to create resource plans and control resource consumption for different database sessions, including setting CPU limits.

9. Does Oracle Database control high CPU utilization automatically?

Oracle Database can automatically manage CPU consumption to some extent, but it’s important to proactively monitor and optimize performance to avoid issues.

10. Can a high number of active sessions contribute to high CPU utilization?

Yes, a high number of active sessions can increase CPU utilization. Load balancing and connection pooling techniques can help manage the number of active sessions.

11. How can I check CPU utilization in Oracle Cloud Autonomous Database?

For Oracle Cloud Autonomous Database, you can use the Oracle Cloud Infrastructure (OCI) Console to check CPU utilization through the Metrics section.

12. Can outdated Oracle database software contribute to high CPU utilization?

Outdated software might lack optimizations and bug fixes present in newer versions. Upgrading to the latest Oracle database software can enhance performance and address high CPU utilization issues.

By following these methods and addressing any identified issues, you can ensure efficient CPU utilization in your Oracle database and maintain optimal performance. Remember to routinely monitor and tune your database to prevent any performance bottlenecks.

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