Is MongoDB/WiredTiger no force no steal?

[Miguel]

Hello, i have some doubts about MongoDB.

I have read that is not possible to make an undo. But as far as I know it uses write ahead logging.

So what information is writting into log? Does it apply a steal policy?

Thank you.

[Keith Bostic]

WiredTiger has a no-steal policy.

WiredTiger does support write-ahead logging, but does not write undo records into the log (which implies that all modifications for an unresolved transaction must fit into memory).