[
https://issues.apache.org/jira/browse/DRILL-3130?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Victoria Markman reopened DRILL-3130:
-------------------------------------
Sean,
I think this fix was rolled back because it was causing regression:
https://issues.apache.org/jira/browse/DRILL-3257
With 1.2.0
#Mon Oct 05 19:59:48 UTC 2015
git.commit.id.abbrev=27a5abc
{code}
0: jdbc:drill:schema=dfs> explain plan for select * from (select a1, b1, c1
from t1 union all select a2, b2, c2 from t2 ) where a1 = 10;
+------+------+
| text | json |
+------+------+
| 00-00 Screen
00-01 Project(a1=[$0], b1=[$1], c1=[$2])
00-02 SelectionVectorRemover
00-03 Filter(condition=[=($0, 10)])
00-04 UnionAll(all=[true])
00-06 Project(a1=[$2], b1=[$1], c1=[$0])
00-08 Scan(groupscan=[ParquetGroupScan
[entries=[ReadEntryWithPath
[path=maprfs:/drill/testdata/subqueries/t1/0_0_0.parquet]],
selectionRoot=maprfs:/drill/testdata/subqueries/t1, numFiles=1,
usedMetadataFile=false, columns=[`a1`, `b1`, `c1`]]])
00-05 Project(a2=[$1], b2=[$0], c2=[$2])
00-07 Scan(groupscan=[ParquetGroupScan
[entries=[ReadEntryWithPath
[path=maprfs:/drill/testdata/subqueries/t2/0_0_0.parquet]],
selectionRoot=maprfs:/drill/testdata/subqueries/t2, numFiles=1,
usedMetadataFile=false, columns=[`a2`, `b2`, `c2`]]])
{code}
> Project can be pushed below union all / union to improve performance
> --------------------------------------------------------------------
>
> Key: DRILL-3130
> URL: https://issues.apache.org/jira/browse/DRILL-3130
> Project: Apache Drill
> Issue Type: Improvement
> Components: Query Planning & Optimization
> Reporter: Sean Hsuan-Yi Chu
> Assignee: Sean Hsuan-Yi Chu
> Fix For: 1.1.0
>
>
> A query such as
> {code}
> Select a from
> (select a, b, c, ..., union all select a, b, c, ...)
> {code}
> will perform Union-All over all the specified columns on the two sides,
> despite the fact that only one column is asked for at the end. Ideally, we
> should perform ProjectPushDown rule for Union & Union-All to avoid them to
> generate results which will be discarded at the end.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
