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Ruben Q L commented on CALCITE-4617: ------------------------------------ Thanks for the clarification [~sylvaincrozon], it makes sense. To go one step further... what about {{sort.fetch}}? Should we apply the same logic and use it only once too (push it to the inner sort and use {{null}} in the top sort, as the PR proposes with the {{offset}}? Even if a duplicated {{fetch}} is not as critical as a duplicated {{offset}} (it does not result in wrong results), it does result in a less optimized plan since the same LIMIT is executed twice. WDYT? > 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: 1.27.0 > > Time Spent: 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)