Good question. I can't find it in any Hive releases. There's hive.auto.convert.join.noconditionaltask (starting in 0.11.0) but not hive.auto.convert.sortmerge.join.noconditionaltask.
Several JIRA issues mention it, including the 0.13.0 release note for HIVE-6098 <https://issues.apache.org/jira/browse/HIVE-6098> "Merge Tez branch into trunk": Hive settings: > > // needed because SMB isn't supported on tez yet > set hive.optimize.bucketmapjoin=false; > set hive.optimize.bucketmapjoin.sortedmerge=false; > set hive.auto.convert.sortmerge.join=false; > set hive.auto.convert.sortmerge.join.noconditionaltask=false; > set hive.auto.convert.join.noconditionaltask=true; > And it was in the Join Optimization <https://cwiki.apache.org/confluence/display/Hive/LanguageManual+JoinOptimization> wikidoc from July 2013 until last month, when Vikram removed it (see page history <https://cwiki.apache.org/confluence/pages/viewpreviousversions.action?pageId=33293167> ): > Auto Conversion to SMB Map Join > > Sort-Merge-Bucket (SMB) joins can be converted to SMB map joins as well. > SMB joins are used wherever the tables are sorted and bucketed. The join > boils down to just merging the already sorted tables, allowing this > operation to be faster than an ordinary map-join. However, if the tables > are partitioned, there could be a slow down as each mapper would need to > get a very small chunk of a partition which has a single key. > > The following configuration settings enable the conversion of an SMB to a > map-join SMB: > > set hive.auto.convert.sortmerge.join=true; > set hive.optimize.bucketmapjoin = true; > set hive.optimize.bucketmapjoin.sortedmerge = true;set > hive.auto.convert.sortmerge.join.noconditionaltask=true; > > -- Lefty On Tue, Aug 4, 2015 at 4:46 PM, William Slacum <wsla...@gmail.com> wrote: > Hi all, > > I've had some questions from users regarding setting > `hive.auto.convert.sortmerge.join.noconditionaltask`. I see, in some > documentation from users and vendors, that it is recommended to set this > parameter. In neither Hive 0.12 nor 0.14 can I find in HiveConf where this > is actually defined and used. Am I correct in thinking that this is just > some cruft that's survived without verification? > > Thanks! >
