I dont' want to go all Hipster™ on all of you, but from a functional point of view, even though SQL was not around as it is today wouldn't it be fair to call VSAM the first NoSQL implementation?
Maybe IDMS is the first one ?
From what I read :
"The "successor" to VSAM and ISAM is DL1, a somewhat hierarchical storage of datasets which was famed for its raw speed. After that came DB2 and SQL as the mediator between the programmer and the database (and thus, the interest in different database concepts faded as all DBs are accessible via SQL)."
Thanks for your feedback! Team Branch