IMS
An older IBM transaction manager and hierarchical database, still running some of the highest-volume systems in the world.
Also written Information Management System, IMS DB, IMS TM
IMS, Information Management System, predates relational databases entirely. It was built for the Apollo programme in the 1960s. It is still in production at many large organisations, often handling the very highest transaction volumes.
It is two products under one name. IMS DB is a hierarchical database, where data is organised as a tree of parent and child segments rather than tables of rows. Retrieval means navigating the hierarchy from the root down, which is extremely fast when your access pattern matches the structure and awkward when it does not. IMS TM is a transaction manager, doing a similar job to CICS.
Programs access it through a call interface rather than SQL, which makes IMS code look quite different from DB2 code.
You will meet it less often than CICS and DB2, but where it is used it is usually central. Banks and telecoms companies with IMS systems tend to have very large ones, and people who understand it are correspondingly scarce.
Related terms
- DB2 for z/OSIBM's relational database on the mainframe, where a great deal of the world's banking and insurance data is stored.
- CICSThe transaction manager that runs online mainframe applications, and the software behind a great many screens bank staff use.
- SubsystemA major piece of software running under z/OS that provides a service to applications, such as a database or a transaction manager.
- Online transaction processingHandling many small pieces of work in real time while someone waits: a card payment, a balance check, a seat booking.
- Legacy systemAn older system still doing essential work. On the mainframe, usually code that has been correct and running for decades.