Jinfeng Ni created DRILL-3716:
---------------------------------
Summary: Drill should push filter past aggregate in order to
improve query performance.
Key: DRILL-3716
URL: https://issues.apache.org/jira/browse/DRILL-3716
Project: Apache Drill
Issue Type: Bug
Components: Query Planning & Optimization
Reporter: Jinfeng Ni
Assignee: Jinfeng Ni
Fix For: 1.2.0
For the following query which has a filter on top of an aggregation, Drill's
currently push the filter pass through the aggregation. As a result, we may
miss some optimization opportunity. For instance, such filter could potentially
been pushed into scan if it qualifies for partition pruning.
For the following query:
{code}
select n_regionkey, cnt from
(select n_regionkey, count(*) cnt
from (select n.n_nationkey, n.n_regionkey, n.n_name
from cp.`tpch/nation.parquet` n
left join
cp.`tpch/region.parquet` r
on n.n_regionkey = r.r_regionkey)
group by n_regionkey)
where n_regionkey = 2;
{code}
The current plan shows a filter (00-04) on top of aggregation(00-05). The
better plan would have the filter pushed pass the aggregation.
The root cause of this problem is Drill's ruleset does not include
FilterAggregateTransoposeRule from Calcite library.
{code}
00-01 Project(n_regionkey=[$0], cnt=[$1])
00-02 Project(n_regionkey=[$0], cnt=[$1])
00-03 SelectionVectorRemover
00-04 Filter(condition=[=($0, 2)])
00-05 StreamAgg(group=[{0}], cnt=[COUNT()])
00-06 Project(n_regionkey=[$0])
00-07 MergeJoin(condition=[=($0, $1)], joinType=[left])
00-09 SelectionVectorRemover
00-11 Sort(sort0=[$0], dir0=[ASC])
00-13 Scan(groupscan=[ParquetGroupScan
[entries=[ReadEntryWithPath [path=classpath:/tpch/nation.parquet]],
selectionRoot=classpath:/tpch/nation.parquet, numFiles=1,
columns=[`n_regionkey`]]])
00-08 SelectionVectorRemover
00-10 Sort(sort0=[$0], dir0=[ASC])
00-12 Scan(groupscan=[ParquetGroupScan
[entries=[ReadEntryWithPath [path=classpath:/tpch/region.parquet]],
selectionRoot=classpath:/tpch/region.parquet, numFiles=1,
columns=[`r_regionkey`]]])
{code}
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