The High_Non_Group index type may be
appropriate for a Low_Fast column.
Note: It is almost always best to use an LF index if
the number of unique values is low (less than 1,000). Consider this index first, if
the column appears in the WHERE clause. Consider
other index types (HG and HNG) only when the
number of unique values is high. For range queries with a high number of unique
values, also consider having an HNG index.