Hmm, but I think people doing OLTP in the 01970s were largely using things like IMS, which used ISAM, on disk, to be able to do small updates to large nested da

Hmm, but I think people doing OLTP in the 01970s were largely using things like IMS, which used ISAM, on disk, to be able to do small updates to large nested datasets very quickly? And for 20+ years one of the major criticisms of relational databases was that they were too slow? And that even today the remaining bastions of IMS cite performance as their main reason for not switching to RDBMSes? I think that if you're processing your transactions on tape drives, your TP isn't OL; it's offline transaction processing. I think Codd's major goal was decoupling program structure from on-disk database structure, not improving performance. There's a lot of the history I don't know, though.