blueflood-core/src/main/java/com/rackspacecloud/blueflood/io/datastax/DBasicMetricsRW.java
@Override
    public DAbstractMetricIO getIO( String rollupType, Granularity granularity ) {

      if( granularity == Granularity.FULL )
        return simpleNumberIO;
      else
        return basicIO;
    }
@Override
    public DAbstractMetricIO getIO( String rollupType, Granularity granularity ) {

      if( granularity == Granularity.FULL )
        return simpleNumberIO;
      else
        return basicIO;
    }
Return the appropriate IO object which interacts with the Cassandra database.

For Preaggregated Metrics, only rollup type is required.
For Basic Numeric Metrics, the granularity is required as metrics_full is handled differently
than the other granularities.

@param rollupType
@param granularity
@return