title: Is there ever any reason for the number of indices to exceed the number of fields? (MySQL or RDBMS in general)?
body: <p>Suppose you have a table with 2 fields, like first name and last name.</p>
  
  <p>If you add a composite index on both fields, that should theoretically take care of indexing the first field. Creating a second index on that field is redundant, as far as I know. To make sure all queries use indexes, you would only have to add an index to last name.</p>
  
  <p>So it seems that the number of indexes on a table should not be larger than the number of fields in a table.</p>
  
  <p>Is that correct or not? If not, why not?</p>