Modern big data workflows, found in e.g., machine learning use cases, often involve iterations of cycles of batch analytics and interactive analytics on temporary data. Whereas batch analytics solutions for large volumes of raw data are well established (e.g., Hadoop, MapReduce), state-of-the-art interactive analytics solutions (e.g., distributed shared nothing RDBMSs) require data loading and/or transformation phase, which is inherently expensive for temporary data.   In this paper, we propose a novel scalable distributed solution for in-situ data analytics, that offers both scalable batch and interactive data analytics on raw data, hence avoiding the loading phase bottleneck of RDBMSs. Our system combines a MapReduce based platform with the recently proposed NoDB paradigm, which optimizes traditional centralized RDBMSs for in-situ queries of raw files. We revisit the NoDB's centralized design and scale it out supporting multiple clients and data processing nodes to produce a new distributed data analytics system we call Distributed NoDB (DiNoDB). DiNoDB leverages MapReduce batch queries to produce critical pieces of metadata (e.g., distributed positional maps and vertical indices) to speed up interactive queries without the overheads of the data loading and data movement phases allowing users to quickly and efficiently exploit their data.   Our experimental analysis demonstrates that DiNoDB significantly reduces the data-to-query latency with respect to comparable state-of-the-art distributed query engines, like Shark, Hive and HadoopDB.
['Yongchao Tian', 'Ioannis Alagiannis', 'Erietta Liarou', 'Anastasia Ailamaki', 'Pietro Michiardi', 'Marko Vukolic']
DiNoDB: Efficient Large-Scale Raw Data Analytics