There is great clarification in @Ixrec's answer at meta.programmers.
Additionally to it being off-topic, the
requirements simply aren't specific enough to make the question answerable.
It might belong, but
the requirements you specify (which would be relevant to an answer) are:
They do not need transactions, ACID, and such. They need to be queried, though.
Which is not enough to rule out any form of data storage at all. Evenusing a simple text file which you read into a
std::map<X, Y>atstartup is enough to allow basic querying. Also, I'm not sure Ibelieve that any use case doesn't require any part of ACID; maybe youdon't need things like rollback but I'm sure everyone wants atomicityand consistency at least.