Systems and methods for query processing and indexing of documents in connection with a content store in a computing system are provided. In various embodiments, an indexing model is provided that is optimized for fast, efficient and scalable retrieval of documents satisfying a query, including the mixed use of forward and inverted indexing representations, including algorithms for achieving a balance between the two representations. When processing queries, fast and efficient generation of reverse chronologically ordered posting lists is enabled for efficient execution of logical operators on query result sets. A term expand index is also provided wherein the overall terms included in the term expand index are decomposed into a plurality of lexicon files, which are combined when convenient for fast, scalable efficiency when performing queries of the content in the content store.