Oracle In-Memory option - size limitations. How does it work?

user8332725

I'm considering using Oracle In-Memory (dual store) and have some questions about the SIZE limitation (INMEMORY_SIZE):

1) Is it limited to 16GB? Or it is unlimited (up to server RAM capacity) while the 16GB limit is when no special license is acquired (base level)

2) What happens if the data going to the In-Memory Columnstore exceeds INMEMORY_SIZE

2. a. A transaction commit will fail?

2. b. A transation will not fail, but message will be returned and then a) a Query will run over IM columnstore will return not complete values (scan only IM)?; or b) a Query will run on both IM columnstore + disk rowstore and then merge?; or c) a Query will run only on IM Columnstore which will evict from memory some portion of data and then load from disk next relevant block of the table (so the IM Columnstore is actually a type of Columnar Buffer cache)?

Thanks