[
https://issues.apache.org/jira/browse/CALCITE-4617?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17354716#comment-17354716
]
duan xiong commented on CALCITE-4617:
-------------------------------------
Hi, [~rubenql] . You mentioned above that :
- If the input is already sorted and we are not reducing the number of tuples,
we bail out
What do you mean? Because if the input is already sorted by join condition, we
still can push offset down.
> Wrong offset when SortJoinTransposeRule pushes a sort node with an offset
> -------------------------------------------------------------------------
>
> Key: CALCITE-4617
> URL: https://issues.apache.org/jira/browse/CALCITE-4617
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.26.0
> Reporter: Sylvain Crozon
> Assignee: Ruben Q L
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.28.0
>
> Time Spent: 1h 50m
> Remaining Estimate: 0h
>
> The SortJoinTransposeRule will push a sort node past a join, and then
> duplicate the sort node on top of the join. When the sort node has an offset,
> we should only apply it once, otherwise we end up skipping twice as many rows
> as we should. The sort node added on top of the join should have a null
> offset.
>
> For example the testSortJoinTranspose6 test checks that for this initial plan
> {code}
> LogicalProject(DEPTNO=[$0], EMPNO=[$2])
> LogicalSort(offset=[2], fetch=[10])
> LogicalJoin(condition=[=($0, $9)], joinType=[right])
> LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
> the SortJoinTransposeRule should convert to
> {code}
> LogicalProject(DEPTNO=[$0], EMPNO=[$2])
> LogicalSort(offset=[2], fetch=[10])
> LogicalJoin(condition=[=($0, $9)], joinType=[right])
> LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
> LogicalSort(offset=[2], fetch=[10])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
> Which will result in applying the offset twice. Instead the LogicalSort on
> top of the join should just have a null offset
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
