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Hudson commented on HIVE-2621: ------------------------------ Integrated in Hive-trunk-h0.21 #1182 (See [https://builds.apache.org/job/Hive-trunk-h0.21/1182/]) HIVE-2621:Allow multiple group bys with the same input data and spray keys to be run on the same reducer. (Kevin via He Yongqiang) heyongqiang : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1226903 Files : * /hive/trunk/common/src/java/org/apache/hadoop/hive/conf/HiveConf.java * /hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java * /hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/plan/ExprNodeDesc.java * /hive/trunk/ql/src/test/queries/clientpositive/groupby10.q * /hive/trunk/ql/src/test/queries/clientpositive/groupby7_map.q * /hive/trunk/ql/src/test/queries/clientpositive/groupby7_map_multi_single_reducer.q * /hive/trunk/ql/src/test/queries/clientpositive/groupby7_noskew.q * /hive/trunk/ql/src/test/queries/clientpositive/groupby7_noskew_multi_single_reducer.q * /hive/trunk/ql/src/test/queries/clientpositive/groupby8.q * /hive/trunk/ql/src/test/queries/clientpositive/groupby9.q * /hive/trunk/ql/src/test/queries/clientpositive/groupby_complex_types_multi_single_reducer.q * /hive/trunk/ql/src/test/queries/clientpositive/groupby_multi_single_reducer.q * /hive/trunk/ql/src/test/queries/clientpositive/multigroupby_singlemr.q * /hive/trunk/ql/src/test/results/clientpositive/groupby10.q.out * /hive/trunk/ql/src/test/results/clientpositive/groupby7_map_multi_single_reducer.q.out * /hive/trunk/ql/src/test/results/clientpositive/groupby7_noskew_multi_single_reducer.q.out * /hive/trunk/ql/src/test/results/clientpositive/groupby8.q.out * /hive/trunk/ql/src/test/results/clientpositive/groupby9.q.out * /hive/trunk/ql/src/test/results/clientpositive/groupby_complex_types_multi_single_reducer.q.out * /hive/trunk/ql/src/test/results/clientpositive/groupby_multi_single_reducer.q.out * /hive/trunk/ql/src/test/results/clientpositive/multi_insert.q.out * /hive/trunk/ql/src/test/results/clientpositive/multigroupby_singlemr.q.out * /hive/trunk/ql/src/test/results/clientpositive/parallel.q.out > Allow multiple group bys with the same input data and spray keys to be run on > the same reducer. > ----------------------------------------------------------------------------------------------- > > Key: HIVE-2621 > URL: https://issues.apache.org/jira/browse/HIVE-2621 > Project: Hive > Issue Type: New Feature > Reporter: Kevin Wilfong > Assignee: Kevin Wilfong > Attachments: HIVE-2621.1.patch.txt, HIVE-2621.D567.1.patch, > HIVE-2621.D567.2.patch, HIVE-2621.D567.3.patch, HIVE-2621.D567.4.patch > > > Currently, when a user runs a query, such as a multi-insert, where each > insertion subclause consists of a simple query followed by a group by, the > group bys for each clause are run on a separate reducer. This requires > writing the data for each group by clause to an intermediate file, and then > reading it back. This uses a significant amount of the total CPU consumed by > the query for an otherwise simple query. > If the subclauses are grouped by their distinct expressions and group by > keys, with all of the group by expressions for a group of subclauses run on a > single reducer, this would reduce the amount of reading/writing to > intermediate files for some queries. > To do this, for each group of subclauses, in the mapper we would execute a > the filters for each subclause 'or'd together (provided each subclause has a > filter) followed by a reduce sink. In the reducer, the child operators would > be each subclauses filter followed by the group by and any subsequent > operations. > Note that this would require turning off map aggregation, so we would need to > make using this type of plan configurable. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira