[jira] [Commented] (HIVE-942) use bucketing for group by
[ https://issues.apache.org/jira/browse/HIVE-942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13551625#comment-13551625 ] Ashutosh Chauhan commented on HIVE-942: --- I think if BucketizedHiveInputFormat is used with map-side aggregation on, this should already work, no? Probably reducer phase will also get created, which is not required and can be optimized away. Is that the optimization we are talking about? use bucketing for group by -- Key: HIVE-942 URL: https://issues.apache.org/jira/browse/HIVE-942 Project: Hive Issue Type: New Feature Components: Query Processor Reporter: Namit Jain Group by on a bucketed column can be completely performed on the mapper if the split can be adjusted to span the key boundary. -- 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
[jira] [Commented] (HIVE-942) use bucketing for group by
[ https://issues.apache.org/jira/browse/HIVE-942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13404730#comment-13404730 ] Lianhui Wang commented on HIVE-942: --- i think in HIVE-931 ,the group by keys must be the same with the sort keys. but in the case that the group by keys contain the sort keys, it may be complete it to use the hash table on the mapper. for example： t is a bucket table, sort by c1,c2. sql: select t.c1,t.c2,t.c3.sum(t.c4) from t group by t.c1,t.c2,t.c3. i think generally that only use the hash table on the mapper.so do not do anything on the reducer. use bucketing for group by -- Key: HIVE-942 URL: https://issues.apache.org/jira/browse/HIVE-942 Project: Hive Issue Type: New Feature Components: Query Processor Reporter: Namit Jain Group by on a bucketed column can be completely performed on the mapper if the split can be adjusted to span the key boundary. -- 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
[jira] [Commented] (HIVE-942) use bucketing for group by
[ https://issues.apache.org/jira/browse/HIVE-942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13233789#comment-13233789 ] Kevin Wilfong commented on HIVE-942: If the table is bucketed and sorted on the group by keys, the group by operator would not need to do a hash, which would help with memory consumption. use bucketing for group by -- Key: HIVE-942 URL: https://issues.apache.org/jira/browse/HIVE-942 Project: Hive Issue Type: New Feature Components: Query Processor Reporter: Namit Jain Group by on a bucketed column can be completely performed on the mapper if the split can be adjusted to span the key boundary. -- 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
