Normal Description
Hop rows internally over-allocate room in the Object[] to prevent excessive re-creation of arrays when a field is added in the next transform for example.
However, in the context of Beam every transform serializes and de-serialized data so we take the re-creation hit regardless. On top of that, more data is being serialized than strictly required, null values in this cases.
The default over-allocation is 10 fields. If we can avoid serializing those it could make a difference.
One of the things we can do is not use RowDataUtil.allocateRowData() in the Beam transforms and functions.
Another is