Oracle SQL Optimization: Top Performance Tips

Here are some tips for optimizing Oracle SQL.

1. Utilize indexes: make sure to create indexes on commonly queried columns in order to speed up query performance. You can use the EXPLAIN PLAN statement to review the query plan and determine if indexes are being utilized.
2. Avoid full table scans by minimizing the use of SELECT statements without a WHERE condition, as this can lead to consuming a significant amount of resources. It is advisable to use a WHERE clause to limit query results as needed.
3. Properly utilize joins: Use INNER JOIN, LEFT JOIN, etc. to avoid querying the database multiple times.
4. Optimize subqueries: try to convert complex subqueries into join queries to improve performance.
5. Avoid using wildcards % and _ in LIKE statements as it can lead to full table scans. It is advisable to minimize their use.
6. Choosing the appropriate data type can improve query performance. For example, using integer data types instead of character data types can reduce storage space and query time.
7. Utilize batch operations: When dealing with a large amount of data, using statements like INSERT INTO SELECT, UPDATE, and DELETE instead of individual operations can improve efficiency.
8. Optimize SQL queries by using appropriate query statements, such as using EXISTS instead of IN subqueries and using UNION ALL instead of UNION.
9. Partitioned tables: For large tables, consider using partitioned tables to improve query performance and management efficiency.
10. Regularly gather statistical information: utilize the DBMS_STATS package to collect statistics for tables, in order to assist in optimizing query plans.

In general, the key to optimizing Oracle SQL is to use indexes effectively, reduce full table scans, optimize query statements and data types, and avoid unnecessary operations.