Show HN: A web API to query HN posts(stories only) in a customized way

As a new user to HN I was curious about all the context I can gain from earlier posts and the native search engine isn't flexible enough(not enough customization).

Made a spring web API over the weekend to query HN stories in a better customized way. I am still to put a front end onto it(shelving it as I am not very good with JS).

It does take significantly longer to query as it scans over like 2.2 million stories and I haven't had enough time to optimize queries(any suggestion will be awesome). However it does get the work done.

Anything that I need to improve?

Any suggestion(s) will be more than welcomed.