IMS
- Started development in 1966 for managing the bill of materials
of the Apollo rocket (Saturn V) and capsule.
So what happened to it?
- Low-level API.
- Difficult to use where your data model is not strictly hierarchical.
- Item is on the "many" side of multiple 1:many
relationships. Can only be in one of the hierarchies.
- many:many relationships
- Established ideas still in use: index-based access paths,
transaction processing.
- But it was pretty much killed off by the relational model.
Those who forget history ...
Forty years later:
- MongoDB, Dynamo, Cassandra, CouchDB, ...
- Part of the "movement".
- Store "documents" which are JSON/BSON objects, which are
hierarchical.
- Low-level API, same modeling difficulties, etc.
- Lax approach to data modeling ("schemaless") complicates applications.
- We will return to these later in the course.