My project of the last few days has been to write a dump utility so that Mayfly can output a database in SQL (similar to mysqldump and similar tools provided with most databases).
Mayfly's dumper can now output CREATE TABLE statements with all of Mayfly's current data types, and likewise INSERT statements for the rows.
So the milestone is that I can now take the standard MIFOS data from the unit tests (DatabaseSetup#getStandardStore()), give it to the dumper, load that dump file back into Mayfly, dump it again, and the first and second dumps will have identical contents.
Now, if the dump just leaves out parts of the data/metadata (as it currently does with constraints, auto-increment values, and binary columns), then this test won't complain (the first dump will omit something, and the reload will just load something different). But it still seems like the dumper might not be too far from finished: this test at least implies that the dumper doesn't blow up on anything in the MIFOS data/metadata, and doesn't generate any invalid SQL.