How to Find And Delete Unused Indexes In Oracle?

To find and delete unused indexes in Oracle, you can use the following steps:

1. First, you need to identify the indexes that are not being used by any queries. You can use the Oracle optimizer to gather information about index usage by enabling the index monitoring feature.
2. Once you have gathered information about index usage, you can query the DBA_INDEXES and DBA_OBJECTS views to find indexes that have not been used in any queries.
3. After identifying the unused indexes, you can drop them using the DROP INDEX statement. Make sure to review the indexes before dropping them to ensure that they are not needed for any future queries.
4. It is recommended to test the performance impact of dropping unused indexes in a non-production environment before making changes in a production environment.

How to analyze index usage in Oracle databases?

There are several methods to analyze index usage in Oracle databases:

1. Use the Oracle SQL Performance Analyzer (SPA): SPA is a tool provided by Oracle that allows you to analyze the performance impact of SQL statements on your database. You can use SPA to identify which indexes are being used by your queries and how often they are being accessed.
2. Query the dynamic performance views: You can query the dynamic performance views in Oracle to get information about index usage. The views like V$SQL, V$SQL_PLAN, and V$SQL_STATS can provide information about the execution plans of SQL statements and whether indexes are being used.
3. Enable and analyze SQL trace: You can enable SQL trace for a specific SQL statement or session in Oracle to capture detailed information about the execution of the statement. By analyzing the trace file, you can determine if the query is using indexes efficiently.
4. Use Oracle Enterprise Manager: Oracle Enterprise Manager provides a variety of performance monitoring and tuning tools that can help you analyze index usage in your database. You can use tools like SQL Tuning Advisor and SQL Access Advisor to identify opportunities for improving index usage.
5. Analyze AWR reports: Automatic Workload Repository (AWR) reports can provide insights into index usage in your database. You can review AWR reports to see which indexes are being used by your queries and identify any indexes that are not being used efficiently.

By using these methods, you can effectively analyze index usage in your Oracle database and optimize the performance of your queries.

How to identify unused indexes in Oracle?

One way to identify unused indexes in Oracle is by using the Oracle provided DBA views and the Index Monitoring feature. Here is a step-by-step guide:

1. Connect to your Oracle database using SQL*Plus or a similar tool.
2. Query the DBA_INDEXES view to get a list of all indexes in the database:

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SELECT index_name, table_name
FROM dba_indexes;

1. Query the DBA_OBJECTS view to get a list of all tables in the database:

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SELECT object_name
FROM dba_objects
WHERE object_type = 'TABLE';

1. Enable monitoring for all indexes by running the following command:

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ALTER INDEX index_name MONITORING USAGE;

1. Let the application run for some time to collect usage data for the indexes.
2. Query the DBA_INDEXES view again to check the monitoring usage for each index:

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SELECT index_name, table_name, monitoring, used, start_monitoring
FROM dba_indexes;

1. Identify the indexes that have never been used by looking at the 'used' column. If the value is 'NO', then the index is likely to be unused.
2. Drop the unused indexes using the following command:

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DROP INDEX index_name;

By following these steps, you can easily identify and drop unused indexes in Oracle, helping to improve database performance and reduce storage space.

What is the best practice for managing indexes in Oracle databases?

1. Regularly review and analyze the performance of existing indexes to identify any potential issues or opportunities for improvement.
2. Only create indexes on columns that are frequently used in queries and where the benefit of the index outweighs the cost of maintaining it.
3. Avoid creating too many indexes on a single table, as this can slow down data modification operations and increase storage requirements.
4. Consider using index compression to reduce the storage space required for indexes.
5. Use the Oracle Index Monitoring feature to track index usage and identify any indexes that are not being used and can be safely removed.
6. Regularly defragment indexes to improve query performance and reduce wasted space.
7. Use the Oracle Database Performance Tuning Advisor to recommend index creation, modification, or removal based on workload analysis.
8. Consider implementing partitioned indexes to improve query performance on large tables.
9. Ensure that statistics are regularly gathered and updated on the indexed columns to ensure the query optimizer can make the most efficient use of the indexes.
10. Monitor and tune the database regularly to ensure optimal index performance.