   _dims = dims;   _schema = schema;   _colsToIx = new int[_schema.length];   _ixToCols = new int[VALID_VALUE_TYPES_LENGTH][];   int[] typeIxCounter = new int[VALID_VALUE_TYPES_LENGTH];   for (int i = 0; i < schema.length; i++) {    int type = schema[i].ordinal();    _colsToIx[i] = typeIxCounter[type]++;   }   for (int i = 0; i < schema.length; i++) {    int type = schema[i].ordinal();    if (_ixToCols[type] == null) {     _ixToCols[type] = new int[typeIxCounter[type]];     typeIxCounter[type] = 0;    }    _ixToCols[type][typeIxCounter[type]++] = i;   }  