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Does sql optimizer make any changes to the current status/plan of the query


I am very new to Toad and I have a very basic question. I have installed Quest SQL optimizer 8.7.1 for Oracle. If I use this for checking better versions of a given query for improved performance, does it only provide me with options or does it actually make any kind of changes to the objects associated with the query or current execution plan or statistics.For example if I were to check for elapsed time with a new index on a relatively huge table, would it actually create the index for this? Please clarify. I only want to know if I can safely use this software just for the sake of comparison without actually making any changes without the approval of my next level of experts. Thanks a lot in advance.

For index recommendation, virtual indexes will be used for simulation during the recommendation stage, there are no physical indexes will be built. If you want to benchmark the recommended indexes, physical indexes will be created for actual execution of your SQL and the created indexes will be dropped after the benchmarking.

For SQL rewrite tuning, there is no change to any database objects. The new syntax will influence Oracle SQL optimizer to generate a better query plan for your specific SQL only. It is a very safe way to tune a SQL.

Thank you.