How to manage a large database when upgrading from 2.0 to 2.1 I am trying to upgrade a site from 2.0.2551 to 2.1.2570. I have ~18k entries and ~28 elements. The upgrade process seems to want to save all the elements again as far as I can tell, is there any way to avoid this or make it quicker? Is there some magical SQL I might play with to do it all?

At present I've had it sat for 14 hours before I gave up...

Incidentally I can legitimately reduce the number of entries to about ~3k and the elements to ~11k as I can just re-import those from an API service - I have tried this and it still takes an awfully long time.

Any advice or previous similar situations you people have run in to would be most helpful :)
In my specific case - upgrading from 2.0.2551 to 2.1.2570 - the issue was caused by there being millions of rows in the craft_entryversions table. One of the migrations in the update needed to loop through every row in that table and do something to it and therefore it took ages.

Simply emptying that table solved the upgrade process for me.

Caveats

Obviously this deletes all your entry versions...so, each entry will just exist at its last known 'live' state. This wasn't a problem for me - but might be for you. 

Its worth noting that this shouldn't affect any drafts users might have made as they are stored in a separate craft_entrydrafts table.

Thanks to Fred Carlsen for helping me think aloud...