[jira] [Updated] (CALCITE-7843) RelMdExpressionLineage should support Window

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-7843?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

ASF GitHub Bot updated CALCITE-7843:
------------------------------------
    Labels: pull-request-available  (was: )

> RelMdExpressionLineage should support Window
> --------------------------------------------
>
>                 Key: CALCITE-7843
>                 URL: https://issues.apache.org/jira/browse/CALCITE-7843
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.42.0
>            Reporter: Alessandro Solimando
>            Assignee: Alessandro Solimando
>            Priority: Major
>              Labels: pull-request-available
>
> RelMdExpressionLineage has no handler for {_}Window{_}, so it falls back to the catch-all _RelNode_ handler ([here|https://github.com/apache/calcite/blob/6484bed4572adbc219b171a9efbbd08a1b662f3a/core/src/main/java/org/apache/calcite/rel/metadata/RelMdExpressionLineage.java#L101-L104]), which always returns null. This happens even for columns that _Window_ simply passes through from its input.
> _RelMdTableReferences_ already supports Window ([here|https://github.com/apache/calcite/blob/6484bed4572adbc219b171a9efbbd08a1b662f3a/core/src/main/java/org/apache/calcite/rel/metadata/RelMdTableReferences.java#L276-L290]), so the two metadata types are not consistent. Any consumer of expression lineage, such as materialized view rewriting, fails on plans containing a {_}Window{_}.
> Reproducer (for {_}RelMetadataTest{_}):
> {code:java}
> @Test void testExpressionLineageWindow() {
>   final RelNode rel = sql("select empno, row_number() over (order by sal) from emp")
>       .toRel();
>   final HepProgram program = new HepProgramBuilder()
>       .addRuleInstance(CoreRules.PROJECT_TO_LOGICAL_PROJECT_AND_WINDOW)
>       .build();
>   final HepPlanner planner = new HepPlanner(program);
>   planner.setRoot(rel);
>   final RelNode window = planner.findBestExp().getInput(0);
>   assertThat(window, instanceOf(Window.class));
>   final RelMetadataQuery mq = window.getCluster().getMetadataQuery();
>   final RexNode ref = RexInputRef.of(0, window.getRowType().getFieldList());
>   final Set<RexNode> r = mq.getExpressionLineage(window, ref);
>   assertThat(String.valueOf(r), is("[[CATALOG, SALES, EMP].#0.$0]"));
> }
> {code}
> The test currently fails as follows:
> {noformat}
> Expected: is "[[CATALOG, SALES, EMP].#0.$0]"
>      but: was "null"
> {noformat}
> Proposed fix: add a _Window_ handler to {_}RelMdExpressionLineage{_}. The output of a _Window_ is all its input columns, in the same order, followed by one column for each window function call. If the expression references only input columns, the handler delegates to the input, the same way the _Sort_ handler does ([here|https://github.com/apache/calcite/blob/6484bed4572adbc219b171a9efbbd08a1b662f3a/core/src/main/java/org/apache/calcite/rel/metadata/RelMdExpressionLineage.java#L422-L425]). If it references a window function call column, the handler returns null.



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