
79MapReduce Family of Large-Scale Data-Processing Systems
returns results as key-value pairs. The Catalog component maintains metadata about
the databases, their location, replica locations, and data-partitioning properties. The
Data Loader component is responsible for globally repartitioning data on a given
partition key upon loading and breaking apart single-node data into multiple smaller
partitions or chunks. The SMS planner extends the HiveQL translator [123] (Section
1.4.3) and transforms SQL into MapReduce jobs that connect to tables stored as les
in HDFS. Abouzeid et al. [4] have demonstrated HadoopDB in action running the
following ...