A Metamorph index may be optimized manually simply by re-issuing the
INDEX $...$ statement
that was used to create it. Instead of producing an error noting that
the index already exists - as would happen with regular or inverted
indexes - the Metamorph index is re-optimized. (If the index is
already fully optimized, the statement returns success immediately.)
Note that the ALTER INDEX statement (here) is an easier method of optimizing indexes.