In order to interpret, enrich, and analyze the streaming data, stream applications often access the data stored in an external database. Although there has been a lot of studies on stream processing, little attention has been paid so far to the join between streaming data and stored data. In this paper, we propose a comprehensive solution called DS-join for distributed processing of the join under the micro-batch model of recently distributed stream processing engines (SPEs), such as spark

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... ming. The micro-batch model performs stream processing as a series of very small batch jobs and is more fault-tolerant in a distributed environment compared with the record-at-a-time model. The DS-join reduces the number of database accesses by using micro-batching. Furthermore, the DS-join optimizes the join operation by minimizing the data shuffling, managing a cache in a distributed SPE, parallelizing the join processing, and balancing the load between the SPE and the external database system. The experimental results using real and synthetic datasets show that, compared with the state-of-the-art methods, the DS-join significantly improves throughput, especially for large databases. INDEX TERMS Micro-batch model, distributed stream processing engine, database system, distributed join processing, cache management, spark streaming.