[
https://issues.apache.org/jira/browse/HIVE-4002?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13750945#comment-13750945
]
Phabricator commented on HIVE-4002:
-----------------------------------
navis has commented on the revision "HIVE-4002 [jira] Fetch task aggregation
for simple group by query".
INLINE COMMENTS
ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java:3631 Right.
I'll fix that.
ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java:6985 It's
the same thing. I just want to be more consistent.
ql/src/java/org/apache/hadoop/hive/ql/exec/Operator.java:582 I need recursive
flush method for implementing this, like what init or close method does. I
think I've broken something rebasing the patch. Can I ask what query was not
working with this patch? Test framework seemed not working recently.
ql/src/java/org/apache/hadoop/hive/ql/exec/FetchOperator.java:493 Flush
should be called to all operators in execution tree, for this patch.
REVISION DETAIL
https://reviews.facebook.net/D8739
To: JIRA, navis
Cc: yhuai
> Fetch task aggregation for simple group by query
> ------------------------------------------------
>
> Key: HIVE-4002
> URL: https://issues.apache.org/jira/browse/HIVE-4002
> Project: Hive
> Issue Type: Improvement
> Components: Query Processor
> Reporter: Navis
> Assignee: Navis
> Priority: Minor
> Attachments: HIVE-4002.D8739.1.patch, HIVE-4002.D8739.2.patch,
> HIVE-4002.D8739.3.patch
>
>
> Aggregation queries with no group-by clause (for example, select count(*)
> from src) executes final aggregation in single reduce task. But it's too
> small even for single reducer because the most of UDAF generates just single
> row for map aggregation. If final fetch task can aggregate outputs from map
> tasks, shuffling time can be removed.
> This optimization transforms operator tree something like,
> TS-FIL-SEL-GBY1-RS-GBY2-SEL-FS + FETCH-TASK
> into
> TS-FIL-SEL-GBY1-FS + FETCH-TASK(GBY2-SEL-LS)
> With the patch, time taken for auto_join_filters.q test reduced to 6 min (10
> min, before).
--
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
