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https://issues.apache.org/jira/browse/DRILL-3420?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Victoria Markman updated DRILL-3420:
------------------------------------
Labels: window_function (was: )
> Final sort can be dropped in some cases when result of window operator is
> already sorted on the same columns
> ------------------------------------------------------------------------------------------------------------
>
> Key: DRILL-3420
> URL: https://issues.apache.org/jira/browse/DRILL-3420
> Project: Apache Drill
> Issue Type: Bug
> Components: Query Planning & Optimization
> Affects Versions: 1.0.0
> Reporter: Victoria Markman
> Assignee: Jinfeng Ni
> Labels: window_function
> Fix For: 1.2.0
>
>
> In the example query, output of the window operator is already sorted on the
> same columns that are specified in "order by clause" Last sort is redundant.
> {code}
> 0: jdbc:drill:schema=dfs> explain plan for select b1, c1, a1, sum(a1)
> over(partition by b1 order by c1, a1) from t1 order by 1,2,3;
> +------+------+
> | text | json |
> +------+------+
> | 00-00 Screen
> 00-01 Project(b1=[$0], c1=[$1], a1=[$2], EXPR$3=[$3])
> 00-02 SelectionVectorRemover
> 00-03 Sort(sort0=[$0], sort1=[$1], sort2=[$2], dir0=[ASC],
> dir1=[ASC], dir2=[ASC])
> 00-04 Project(b1=[$0], c1=[$1], a1=[$2], EXPR$3=[CASE(>($3, 0),
> $4, null)])
> 00-05 Window(window#0=[window(partition {0} order by [1, 2]
> range between UNBOUNDED PRECEDING and CURRENT ROW aggs [COUNT($2),
> $SUM0($2)])])
> 00-06 SelectionVectorRemover
> 00-07 Sort(sort0=[$0], sort1=[$1], sort2=[$2], dir0=[ASC],
> dir1=[ASC], dir2=[ASC])
> 00-08 Scan(groupscan=[ParquetGroupScan
> [entries=[ReadEntryWithPath [path=maprfs:///drill/testdata/subqueries/t1]],
> selectionRoot=/drill/testdata/subqueries/t1, numFiles=1, columns=[`b1`, `c1`,
> `a1`]]])
> {code}
> Note to QA: when this enhancement is implemented, we need to make sure that
> we have cases where sort order is destroyed by subsequent operation on top of
> window. In these cases "sort should still be planned.
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