An experimental comparison of complex object implementations for big data systems

Many cloud-based data management and analytics systems support complex objects. Dataflow platforms such as Spark and Flink allow programmers to manipulate sets consisting of objects from a host programming language (often Java). Document databases such as MongoDB make use of hierarchical interchange formats---most popularly JSON---which embody a data model where individual records can themselves contain sets of records. Systems such as Dremel and AsterixDB allow complex nesting of data structures. Clearly, no system designer would expect a system that stores JSON objects as text to perform at the same level as a system based upon a custom-built physical data model. The question we ask is: How significant is the performance hit associated with choosing a particular physical implementation? Is the choice going to result in a negligible performance cost, or one that is debilitating? Unfortunately, there does not exist a scientific study of the effect of physical complex model implementation on system performance in the literature. Hence it is difficult for a system designer to fully understand performance implications of such choices. This paper is an attempt to remedy that.