What should be done with unnecessary or redundant indexes?

Unnecessary or redundant indexes can consume valuable storage space and can negatively impact write performance, as the database must update these indexes with every insert, update, or delete operation. Thus, removing these indexes is a proactive approach to optimize database performance.

By deleting unnecessary indexes, you can improve the efficiency of your database operations. This cleanup helps ensure that the remaining indexes are meaningful and effectively enhance query performance without the overhead of maintaining indexes that do not contribute to the overall efficiency or effectiveness of data retrieval.

Keeping redundant indexes around for potential future use is generally not advisable, as the potential benefits do not outweigh the performance costs. Upgrading them to compound indexes doesn't address the issue of redundancy; it can complicate the index management process further. Archiving them could provide a means to preserve the indexes but does not alleviate the performance implications of having them in the live environment. Therefore, the optimal action is to delete unnecessary or redundant indexes to maintain an efficient database system.