# now we can derive whichever other hashes or arrays
  # we might want from the above data.  having a list
  # of column names is always handy:
  my @COL_NAMES = map $_->{name}, @COL_INFO;

  # and we might want to look up columns by name:
  my %COL_BY_NAME; @COL_BY_NAME{ @COL_NAMES } = @COL_INFO;

  # and to find the index of a column name:
  my %COL_INDEX; @COL_INDEX{ @COL_NAMES } = 0 .. $#COL_INFO;