I've worked contracts in UK banks for a number of years now. Nothing on the mainframes but I know some of the guys that do work on those and, despite the constant stream of flavour-of-the-month tech that we talk about constantly in places like HN, the mainframes work well and will not be replaced any time soon.
The dev cycle for releases and whatnot is incredibly long due to testing and, lets be honest, fear, in case something breaks but when it comes to battle-tested technology, mainframes and DB2 are right up there.
I do know of some code that's over 40 years old and still runs at the core of one of the big banks...
MongoDB, despite its capabilities, is... an odd choice imo! Not trying to second-guess but if I was in that meeting I would have certainly raised an eyebrow.
The dev cycle for releases and whatnot is incredibly long due to testing and, lets be honest, fear, in case something breaks but when it comes to battle-tested technology, mainframes and DB2 are right up there.
I do know of some code that's over 40 years old and still runs at the core of one of the big banks...
MongoDB, despite its capabilities, is... an odd choice imo! Not trying to second-guess but if I was in that meeting I would have certainly raised an eyebrow.
Good luck to them.