xuzifu666 commented on code in PR #5040:
URL: https://github.com/apache/calcite/pull/5040#discussion_r3464468086
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core/src/test/resources/sql/sub-query.iq:
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@@ -2540,11 +2541,12 @@ EnumerableCalc(expr#0..5=[{inputs}], expr#6=[NOT($t3)],
expr#7=[IS NOT NULL($t3)
EnumerableSort(sort0=[$2], dir0=[ASC])
EnumerableCalc(expr#0..7=[{inputs}], EMPNO=[$t0], SAL=[$t5],
DEPTNO=[$t7])
EnumerableTableScan(table=[[scott, EMP]])
- EnumerableSort(sort0=[$1], dir0=[ASC])
- EnumerableCalc(expr#0..1=[{inputs}], expr#2=[false], expr#3=[1],
expr#4=[<=($t1, $t3)], cs=[$t2], DEPTNO=[$t0], rn=[$t1], $condition=[$t4])
- EnumerableWindow(window#0=[window(partition {0} rows between UNBOUNDED
PRECEDING and CURRENT ROW aggs [ROW_NUMBER()])], constants=[[false]])
- EnumerableCalc(expr#0..2=[{inputs}], DEPTNO=[$t0])
- EnumerableTableScan(table=[[scott, DEPT]])
+ EnumerableCalc(expr#0..2=[{inputs}], expr#3=[1], expr#4=[<=($t2, $t3)],
proj#0..2=[{exprs}], $condition=[$t4])
Review Comment:
This fix altered the sorting metadata derivation for the window operator,
resulting in a legitimate change to the execution plan structure of two
existing !plan tests, but the computation results remain unchanged.
Specific changes: Previously, the collation derivation for
`EnumerableWindow` was optimistic, claiming to retain the input sorting. With
`CalcRelSplitter` inheriting the original `Calc`'s collation, the optimizer
would push `Sort` down onto the `Window` and merge it with the outer `Calc`.
Therefore, the original plan was:
```
EnumerableSort
EnumerableCalc(condition + window output)
EnumerableWindow
```
After the fix, `EnumerableWindow` no longer claims any sorting, and
`CalcRelSplitter` no longer inherits the contaminated collation. `Sort` can
only stop at the `Window`, wrapped in an outer `Calc` for projection. The plan
becomes:
```
EnumerableCalc(projection)
EnumerableSort
EnumerableCalc(condition)
EnumerableWindow
```
Both are logically equivalent; only the relative positions of `Sort` and the
projected `Calc` have changed. Therefore, only the expected output of these two
!plan blocks was updated, without modifying any result data.This also ensures
complete consistency with the PostgreSQL sorting results.
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