  Finding patterns in data and being able to retrieve information from those
patterns is an important task in Information retrieval. Complex search
requirements which are not fulfilled by simple string matching and require
exploring certain patterns in data demand a better query engine that can
support searching via structured queries. In this article, we built a
structured query engine which supports searching data through structured
queries on the lines of ElasticSearch. We will show how we achieved real time
indexing and retrieving of data through a RESTful API and how complex queries
can be created and processed using efficient data structures we created for
storing the data in structured way. Finally, we will conclude with an example
of movie recommendation system built on top of this query engine.
