Systems and methods are described herein that can implemented by a middle tier of a multi-tier data retrieval system to select data operation(s) that correspond to a query. The query may be received from a front tier. The selection is performed by comparing the query to a query template associated with each data operation. The query template for each data operation includes an algebraic description of queries that each respective data operation can satisfy. The selected data operation(s) are then executed against a data service to obtain data, which is then provided to the front tier. In some embodiments, an execution plan may be created by the middle tier for satisfying the query. The execution plan can include the selected data operation(s) and post-processing step(s). The post-processing step(s) can be applied to the obtained data to satisfy the query. The post-processed data is then provided to the front tier.