Namit Jain created HIVE-3952: -------------------------------- Summary: merge map-job followed by map-reduce job Key: HIVE-3952 URL: https://issues.apache.org/jira/browse/HIVE-3952 Project: Hive Issue Type: Improvement Reporter: Namit Jain
Consider the query like: select count(*) FROM ( select idOne, idTwo, value FROM bigTable JOIN smallTableOne on (bigTable.idOne = smallTableOne.idOne) ) firstjoin JOIN smallTableTwo on (firstjoin.idTwo = smallTableTwo.idTwo); where smallTableOne and smallTableTwo are smaller than hive.auto.convert.join.noconditionaltask.size and hive.auto.convert.join.noconditionaltask is set to true. The joins are collapsed into mapjoins, and it leads to a map-only job (for the map-joins) followed by a map-reduce job (for the group by). Ideally, the map-only job should be merged with the following map-reduce job. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira