| Although we are not expected to be persistent per se,
we may be written out by the sorter temporarily. So
we need to be able to write ourselves out and read
ourselves back in. We rely on formatable to handle
situations where value is null.
Why would we be called to write ourselves out if we
are null? For scalar aggregates, we don't bother
setting up the aggregator since we only need a single
row. So for a scalar aggregate that needs to go to
disk, the aggregator might be null.
exception:
IOException - on error
See Also: java.io.Externalizable.writeExternal |
