[jira] [Created] (CALCITE-841) When the argument of window functions is an expression, redundant windows could be generated

["Sean Hsuan-Yi Chu (JIRA)" <ji...@apache.org>]

Sean Hsuan-Yi Chu created CALCITE-841:
-----------------------------------------

             Summary: When the argument of window functions is an expression, redundant windows could be generated
                 Key: CALCITE-841
                 URL: https://issues.apache.org/jira/browse/CALCITE-841
             Project: Calcite
          Issue Type: Bug
            Reporter: Sean Hsuan-Yi Chu
            Assignee: Sean Hsuan-Yi Chu


Firstly of all, this issue happens when HepPlanner is used with ProjectToWindowRule.PROJECT rule.

A query with this pattern:
{code}
select fn(col) over w, fn(expr) over w
from ...
{code}
will generate two "LogicalWindow" even if we have only an identical window frame.

For example, 
{code}
select sum(deptno ) over(partition by deptno order by sal) as sum1, 
sum(deptno + deptno) over(partition by deptno order by sal) as sum2
from emp
{code}
gives:
{code}
LogicalProject($0=[$2], $1=[$4])
  LogicalWindow(window#0=[window(partition {1} order by [0] range between UNBOUNDED PRECEDING and CURRENT ROW aggs [SUM($3)])])
    LogicalProject(SAL=[$0], DEPTNO=[$1], $2=[$2], $3=[+($1, $1)])
      LogicalProject(SAL=[$5], DEPTNO=[$7], $2=[$9])
        LogicalWindow(window#0=[window(partition {7} order by [5] range between UNBOUNDED PRECEDING and CURRENT ROW aggs [SUM($7)])])
          LogicalTableScan(table=[[CATALOG, SALES, EMP]])
{code}



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