Most people, I think, interpret MVCC as an alternative to two-phase locking for both reading and writing data.

Bernstein was later hired by DEC, who had funded much of his earlier research. He had published a claiming there only two or three four ways to concurrency control, only so many ways to recovery, etc., so there were only a small number of ways to write a database system, so people were wasting their time thinking out it any. We argued quite a bit since Rdb/ELN essentially broke his argument. He eventually conceded the point (this was around 1983/84).

He never mentioned an earlier paper on multi-generational concurrency control, and I was certainly unaware of it. It would have been very interesting reading.

As for pre-Interbase commercial use of multi-generational concurrency control, of course there was one — DEC’s Rdb/ELN. Not only did it use much the same technology as InterBase, it was also called JRD.

The inspiration for multi-generational concurrency control was a database system done by Prime that supported page level snapshots. The intention of the feature was to give a reader a consistent view of the database without blocking writers. The idea intrigued me as a very useful characteristic of a database system. Sometime later, and I member the exact instant, it occurred to me that a single mechanism could be used to provide a static snapshot, provide a transaction recovery mechanism, and handle concurrency control. The DEC JRD started a few days later as an advanced development project, and was later picked up by DEC’s storage systems as the software core for a database machines based on the HSC disk controller, code named "Hawk". The first product in the family was Jayhawk, a dedicated server implementation on the MicroVax-II using Dave Cutler’s VAX Eln operating system. Cutler took a fancy to JRD and decided he’d rather have a full blown relational database than an ISAM system, so we agreed to do a first release on ELN and ELN’s development system, VMS.