As we can see, the utility first points out that neither the idx_uemp_id index nor the idx_fnumber are necessary and it points out why. The first, idx_uemp_id, is redundant because the primary key already ensures that emp_id values have to be unique. As for idx_fnumber, it is also redundant because of idx_ufnumber, a UNIQUE type index which also works as a regular index. Then it points out that idx_full_name_dup is also not necessary. In this case it is a duplicate of the idx_full_name index since it contains the exact same columns on the same order.

Notice that it also indicates that idx_name, idx_surname and even the PRIMARY INDEX on emp_id might be redundant. This happens because we are dealing with BTREE type indexes and for this type of indexes an index X is redundant to an index Y if and only if the first n columns in X also appear in Y.

Given that we are using InnoDB engine, it also warns us that `idx_uemp_id`, `ìdx_id_name`, `idx_id_hdate` and `idx_id_bday` might not be needed. This happens because, in InnoDB, secondary indexes contain the primary key columns for the row that are not in the secondary index.

It must be noted however that these are just indications, they must not be followed blindly because redundant indexes can be useful depending on how you use (query) your tables.

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