HELP INDEX does not report information about hash or join indexes.
HELP INDEX does report on the indexes defined on hash and join indexes, as explained in the following table:
|FOR this type of index …||Information is reported on the following index characteristics …|
See Specifying the Primary Index for a Hash Index for information about these primary indexes.
|Join||Primary index defined for the join index.
Any secondary indexes defined on the join index.
HELP INDEX does not report the ordering columns for a covering index or value-ordered join index. SHOW TABLE reports these columns (see SHOW object).