How to use and optimize Oracle indexes.

Using indexes can improve query efficiency. Here are some methods for using and optimizing Oracle indexes: 1. Ensure that columns in the table have indexes: This can be done by creating primary keys, unique constraints, or creating indexes on the columns in the table. 2. Consider using composite indexes: Composite indexes are indexes based on multiple columns and can improve query efficiency. When creating composite indexes, consider the combination of columns frequently used in queries. 3. Avoid using functions on indexed columns: Using functions on indexed columns can result in index inefficiency. Handle data using functions in queries instead of on indexes. 4. Avoid type conversions on indexed columns: Type conversions on indexed columns can cause index inefficiency. Use values of the same type in queries to avoid type conversions. 5. Analyze indexes: Use Oracle’s statistical analysis tools to determine if indexes are being used effectively and if optimization is needed. 6. Avoid excessive indexing: Excessive indexing increases the overhead of inserts, updates, and deletes, and may cause indexes to be ineffective. Only create necessary indexes and avoid unnecessary ones. 7. Regularly reorganize indexes: When data in a table changes, indexes may become fragmented. Reorganize indexes to improve query efficiency. 8. Specify indexes using hints: Use hints in queries to specify the use of a particular index, forcing the query to use the specified index. 9. Use bitmap indexes: For columns with few distinct values, consider using bitmap indexes to reduce storage space and improve query efficiency. 10. Use index merging: When a query involves multiple indexes, use index merging to improve query efficiency. These are some commonly used methods for using and optimizing Oracle indexes. Specific strategies for use and optimization can be adjusted according to the actual situation.