Triggering re-import when yottadb differs

[medwar99]

Current triggering of the ABP import looks at if a) the ABP data has changed (makes sense) and b) if the yotta database doesn't match what is expected (trickier).

The difficulty with (b) is that we currently look at a sha256sum on $ydb_gbldir, but this isn't a direct reference to the data contained in the ydb database and instead points to yottadb.gld which represents the globals available in the database. In addition, requests made via the API will actually alter the actual yottadb.dat file which stores the data, we don't want to reload the data every time someone makes a request.

At the moment, the checksum for $ydb_gbldir only indicates that the yotta database has been created, not that any data has been ingested. We produce it after the load succeeds, but the sha will be the same no matter what data is actually in the database.

Is there something we could hash instead which shows the database in it's freshly imported state, that isn't affected by user query requests. This may be overkill.