Hello, Data about my spark job is below. My source data is only 916MB (stage 0) and 231MB (stage 1), but when i join the two data sets (stage 2) it takes a very long time and as i see the shuffled data is 614GB. Is this something expected? Both the data sets produce 200 partitions.
Stage IdDescriptionSubmittedDurationTasks: Succeeded/TotalInputOutputShuffle ReadShuffle Write2saveAsTable at Driver.scala:269 <http://sparkhs.rfiserve.net:18080/history/application_1437606252645_1034031/stages/stage?id=2&attempt=0> +details 2015/10/22 18:48:122.3 h 200/200 614.6 GB1saveAsTable at Driver.scala:269 <http://sparkhs.rfiserve.net:18080/history/application_1437606252645_1034031/stages/stage?id=1&attempt=0> +details 2015/10/22 18:46:022.1 min 8/8 916.2 MB3.9 MB0saveAsTable at Driver.scala:269 <http://sparkhs.rfiserve.net:18080/history/application_1437606252645_1034031/stages/stage?id=0&attempt=0> +details 2015/10/22 18:46:0235 s 3/3 231.2 MB4.8 MBAm running Spark 1.4.1 and my code snippet which joins the two data sets is: hc.sql(query). mapPartitions(iter => { iter.map { case Row( ... ... ... ) } } ).toDF() .groupBy("id_1", "id_2", "day_hour", "day_hour_2") .agg($"id_1", $"id_2", $"day_hour", $"day_hour_2", sum("attr1").alias("attr1"), sum("attr2").alias("attr2")) Please advise on how to reduce the shuffle and speed this up. ~Pratik