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https://issues.apache.org/jira/browse/CALCITE-7616?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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leishp reassigned CALCITE-7616:
-------------------------------
Assignee: (was: leishp)
> ProjectToLogicalProjectAndWindowRule should not match non-logical Project
> nodes with JDBC convention
> ----------------------------------------------------------------------------------------------------
>
> Key: CALCITE-7616
> URL: https://issues.apache.org/jira/browse/CALCITE-7616
> Project: Calcite
> Issue Type: Bug
> Components: core
> Reporter: leishp
> Priority: Major
> Labels: pull-request-available
>
> When a JDBC schema's dialect supports window functions (e.g. MySQL,
> PostgreSQL), a query with CTE and RANK() throws AssertionError during
> VolcanoPlanner optimization:
> {code:java}
> AssertionError: Relational expression
> LogicalWindow.JDBC.TEST.[]
> has calling-convention JDBC.TEST but does not implement the required
> interface
> 'interface org.apache.calcite.adapter.jdbc.JdbcRel' of that convention
> {code}
> h3. Reproduction
> A JDBC schema with MySQL dialect ({{{}supportsWindowFunctions() = true{}}}),
> and a query with CTE + RANK():
> {code:sql}
> WITH ranked AS (
> SELECT customer_name, contract_amount,
> RANK() OVER (ORDER BY contract_amount DESC) AS rnk
> FROM sales_data
> )
> SELECT customer_name FROM ranked WHERE rnk <= 3
> {code}
> h3. Root cause
> {{ProjectToLogicalProjectAndWindowRule}} passes the parent {{{}Project{}}}'s
> traitSet directly to {{LogicalWindow.create()}} via {{{}CalcRelSplitter{}}}.
> When the parent is a {{JdbcProject}} (JDBC convention), the generated
> {{LogicalWindow}} inherits the JDBC convention but does not implement the
> {{JdbcRel}} interface, causing an AssertionError in
> {{{}VolcanoPlanner.registerImpl{}}}.
> {code:java}
> // ProjectToWindowRule.java:161 — passes project.getTraitSet() directly
> final LogicalCalc calc =
> new LogicalCalc(project.getCluster(), project.getTraitSet(), // JDBC
> convention leaks in
> project.getHints(), input, program);
> {code}
> This is related to CALCITE-3352 (wrong collation on generated Window) — both
> bugs share the same root cause: {{ProjectToWindowRule}} blindly propagates
> the parent's traitSet to the generated {{{}LogicalWindow{}}}. Danny Chen
> commented on CALCITE-3352:
> {quote}We should limit this rule to only match logical nodes because it is a
> plan rewrite.
> {quote}
> h3. Fix
> Force {{Convention.NONE}} when creating the temporary {{{}LogicalCalc{}}}, so
> that {{LogicalWindow}} never inherits a non-NONE convention:
> {code:java}
> // ProjectToWindowRule.java
> final RelTraitSet traitSet =
> project.getTraitSet().replace(Convention.NONE);
> final LogicalCalc calc =
> new LogicalCalc(project.getCluster(), traitSet,
> project.getHints(), input, program);
> {code}
> h3. Impact
> - When dialect supports window functions: window function is pushed down to
> database via {{{}JdbcProject{}}}. Correct behavior.
> - When dialect does NOT support window functions:
> {{ProjectToLogicalProjectAndWindowRule}} fires on {{LogicalProject(NONE)}} as
> before. No change.
> - No existing tests broken (verified {{RelOptRulesTest}} 902/902 passed).
> h3. Scope
> This is a targeted fix for the convention issue only. The collation issue
> (CALCITE-3352) is tracked separately.
> h3. Test
> A JUnit test {{JdbcWindowConventionTest}} is provided in the PR, using HSQLDB
> in-memory database with MySQL dialect override to reproduce the bug without
> an external database.
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