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{"id":1902,"date":"2021-04-07T06:00:00","date_gmt":"2021-04-07T11:00:00","guid":{"rendered":"https:\/\/www.bigdatainrealworld.com\/?p=1902"},"modified":"2023-02-19T07:31:31","modified_gmt":"2023-02-19T13:31:31","slug":"what-is-the-difference-between-groupbykey-and-reducebykey-in-spark","status":"publish","type":"post","link":"https:\/\/www.bigdatainrealworld.com\/what-is-the-difference-between-groupbykey-and-reducebykey-in-spark\/","title":{"rendered":"What is the difference between groupByKey and reduceByKey in Spark?"},"content":{"rendered":"\nBoth reduceByKey and groupByKey result in wide transformations which means both triggers a shuffle operation.<\/p>\n\n\n\n
The key difference between reduceByKey and groupByKey is that reduceByKey does a map side combine and groupByKey does not do a map side combine.<\/span><\/p>\n\n\n\nLet\u2019s say we are computing word count on a file with below line<\/span><\/p>\n\n\n\nRED GREEN RED RED<\/span><\/p>\n\n\n\nAt runtime let\u2019s say we end up with 2 partitions.<\/span><\/p>\n\n\n\nPartition 1\nRED\nGREEN\nPartition 2\nRED\nRED<\/pre>\n\n\n\n