Hive version 0.12.0 To enable Map side join, we enable:
set hive.auto.convert.join=true; set hive.auto.convert.join.noconditionaltask = true; set hive.auto.convert.join.noconditionaltask.size = 128000000; However, when we also set: hive.optimize.cp=false, Map side join will fail with following error: hadoop@node76-99:/mnt/szhu/queries$ hive -f test-mapjoin.q Logging initialized using configuration in jar:file:/home/hadoop/hive-0.12.0/lib/hive-common-0.12.0.jar!/hive-log4j.properties Hive history file=/tmp/hadoop/hive_job_log_26f6c6bb-21ab-4e33-851c-3c5d3db63bff_166055775.txt Total MapReduce jobs = 1 Execution log at: /tmp/hadoop/.log 2014-08-06 12:09:02 Starting to launch local task to process map join; maximum memory = 932118528 Execution failed with exit status: 2 Obtaining error information Task failed! Task ID: Stage-5 Logs: /tmp/hadoop/hive.log FAILED: Execution Error, return code 2 from org.apache.hadoop.hive.ql.exec.mr.MapredLocalTask
