…rage.

Increases the copy rate from 1.01MB/s to 5.58MB/s on a sample of transactions, or 180000 objects to 417000 objects.

Outstanding issues:

zodbconvert's incremental mode doesnt work.
zc.zlibstorage doesn't work on the destination during the copy. Maybe that's ok.
Because you could just not use a decompressing wrapper on the source to get identical copies.
Logging is messed up.

…ations when using incremental zodbconvert.

This is still not fully safe, though: If you start copying, stop, start again in incremental mode, because one copies by OID and the other by TID you could wind up missing data.

Needs more thought.

Add tests with blobs, more incremental testing, and tests with history-free destinations.

This found, and added a workaround for, zopefoundation/ZODB#330

…urds.

We'll manually transform the data there, allowing us to replace the wrappers copyTransactionsFrom method with our own optimized implementation in registerDB.

…unate) interaction betwenn incremental copies and fast copies.