Index used summary

Contains a row of information for each permanent index that an SQL statement used. This can be used to quickly tell if any of the permanent indexes were used to improve the performance of a query. Permanent indexes are typically necessary to achieve optimal query performance. This information can be used to determine how often a permanent index was used by in the statements that were monitored. Indexes that are never (or very rarely) used should probably be dropped to improve the performance of inserts updates and deletes to a table. Before dropping the index you may also want to look at the last used date in the Description information for the index and in the Show index information for the table the index is based on.