The nullmap is currently always written to the tuple layout for all columns
even if there are no nullable columns described in the schema.
The same is true and can be done for varlen table.
Seems, we can extend this idea to every single tuple and still have the ability to compare key/value content fast as byte arrays.
Apparently, this will work for rows of same schema version, but we shouldn't bother about the schema version,
because anyway, old row will be upgraded to the newer version before comparison according to the live-schema concept.
Let's skip an empty nullmap and write just a flag instead.
Let's skip an empty varlen table and write just a flag instead.