Excution Model of MonetDB (column-at-a-time...or?)

Greetings,

The current query engine of the MonetDB...what model of processing does it follow....(column-at-a-time, tuple-at-a-time, vector-at-a-time)?

one last question....

Has the X100 query engine ever been published as opensource in the older releases of MonetDB?

Thanks a lot in advance,

Best Regards,

Mahmoud Mohsen