Investigating SQL performance is very big topic in Oracle worlds. Many times we hit performance issue during daily control. Many of performance problems are related with bad coding, changed plan, missing index or missing statistics. It my also related with server components too.

Investigating SQL performance in an Oracle database involves analyzing and identifying performance bottlenecks and optimizing the execution of SQL statements.

Oracle database has most effective tools&guns for can identify erformance bottlenecks. In this post, I want to share my performance issue approach for SQL related problems.

Here are some steps to help you investigate SQL performance in Oracle:

Identify the problematic SQL statements:
Determine which SQL statements are causing performance issues. This can be done by examining application logs, using Oracle’s performance monitoring tools, or capturing SQL statements with high resource usage.

Collect performance statistics:
Gather relevant performance statistics to gain insights into the behavior of the SQL statements. Oracle provides various tools like Automatic Workload Repository (AWR) and Active Session History (ASH) that can capture and store performance data over time.

Analyze query execution plans:
Examine the execution plans of the SQL statements to understand how Oracle is executing them. The execution plan outlines the steps taken by Oracle to retrieve and process the data. Use the EXPLAIN PLAN statement or Oracle’s SQL tuning tools to generate and analyze the execution plans.

Review indexes and table statistics:
Check the indexes on the tables involved in the SQL statements. Ensure that appropriate indexes exist, and they are being utilized efficiently. Analyze the table statistics and ensure they are up-to-date using the ANALYZE statement or the DBMS_STATS package.

Identify performance bottlenecks:
Look for potential performance bottlenecks in the SQL statements. This can include inefficient joins, missing or ineffective indexes, large result sets, or excessive disk I/O. Use Oracle’s performance monitoring tools, query execution plans, and performance statistics to identify the areas causing performance degradation.

Optimize SQL statements:
Once the performance bottlenecks are identified, optimize the SQL statements to improve performance. This can involve rewriting the queries, adding or modifying indexes, using query hints, or changing the data access patterns. Oracle’s SQL tuning tools, like SQL Tuning Advisor and SQL Access Advisor, can assist in generating recommendations for SQL optimization.

Monitor and fine-tune:

Continuously monitor the performance of the SQL statements and the overall database. Regularly review and fine-tune the queries, indexes, and other database components as the data and workload evolve. If you have OEM than do not forget to use it! Its most powerful tools for SQL related problems

Remember that SQL performance tuning is an iterative process, and it requires a deep understanding of the database structure, SQL language, and Oracle’s performance optimization techniques.