Does mdserver always open before engine and close after engine

[markcmiller86]

In improving ZipWrapper, I am wondering if it is always true that any timestep VisIt moves to, the mdserver always opens it before the engine ever does and then always closes (frees up) a timestep after the engine does? Is that always true?

[markcmiller86]

I think this is only true when Treat all dbs as time varying is enabled. Otherwise, the mdserver often uses what it knows about the database from the timestep it opened it at to infer/predict what is known about the current timestep. And, now that I think about it, ZipWrapper should probably always operate that way anyways.