RDBDocumentStore uses two different code paths for updates, one which using string append operations in the database. Which code path is followed depends on the current modcount of the document and the remaining size in the DATA column.
It would be good if appending updates could be turned off, because:
1) it might be a last resort for DBs where the append code for some reason does not work (theoretical at this point), and
2) it makes it easier to reliably test both code paths.