[
https://issues.apache.org/jira/browse/DRILL-3412?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14637601#comment-14637601
]
Jinfeng Ni commented on DRILL-3412:
-----------------------------------
View with fewer columns will not help, I believe, since in query planning, the
view will be replaced with its view ddl statement, which will query against the
base TPCDS table.
You can create another table T2 in parquet (assume you use parquet format) from
the original table T1, such that T2 only contains the columns referenced in the
query. Then, do a performance comparison, to see the impact of project pushdown
on window function.
{code}
Select some_window_function from T1;
SELECT some_window_function from T2;
{code}
> Projections are not getting push down below Window operator
> -----------------------------------------------------------
>
> Key: DRILL-3412
> URL: https://issues.apache.org/jira/browse/DRILL-3412
> Project: Apache Drill
> Issue Type: Bug
> Components: Query Planning & Optimization
> Reporter: Aman Sinha
> Assignee: Jinfeng Ni
> Priority: Blocker
> Fix For: 1.2.0
>
>
> The plan below shows that the 'star' column is being produced by the Scan and
> subsequent Project. This indicates projection pushdown is not working as
> desired when window function is present. The query produces correct results.
> {code}
> explain plan for select min(n_nationkey) over (partition by n_regionkey) from
> cp.`tpch/nation.parquet` ;
> 00-00 Screen
> 00-01 Project(EXPR$0=[$0])
> 00-02 Project(w0$o0=[$3])
> 00-03 Window(window#0=[window(partition {2} order by [] range
> between UNBOUNDED PRECEDING and UNBOUNDED FOLLOWING aggs [MIN($1)])])
> 00-04 SelectionVectorRemover
> 00-05 Sort(sort0=[$2], dir0=[ASC])
> 00-06 Project(T1¦¦*=[$0], n_nationkey=[$1], n_regionkey=[$2])
> 00-07 Scan(groupscan=[ParquetGroupScan
> [entries=[ReadEntryWithPath [path=classpath:/tpch/nation.parquet]],
> selectionRoot=/tpch/nation.parquet, numFiles=1, columns=[`*`]]])
> {code}
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
