when you update, you just dump the old nxt_db directory into the nxt_db in the unzip directory of the new version, and the blockchain won't be downloaded -just as with before, when you could just dump the blocks.nrs and transactions.nrs into the new version.
only then it would crash very often, and now with sql it hopefully won't.
At least that's what I understand from it.
Well, I see. I don't think we were talking about the 'manual performance of upgrading' but the runtime performance, though.
But, you are right. That's the idea of having a database which is able to handle transactions, rollbacks, caching, indexing etc. at once. Much better than inventing your own serialization format. +1