Optimize metadata query with distinct + limit #25460
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Pull Request Overview
This PR optimizes metadata queries by introducing special handling for DistinctLimitNode in the MetadataQueryOptimizer and updating the AggregationNode optimization flow.
- Introduces a new visitor method for DistinctLimitNode tests.
- Refactors AggregationNode handling to use a common Optional-based table scan optimization.
- Adds a new test case for DISTINCT queries with LIMIT in the Iceberg plugin.
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| plugin/trino-iceberg/src/test/java/io/trino/plugin/iceberg/TestMetadataQueryOptimization.java | Adds a new test case verifying the plan for "SELECT DISTINCT ... LIMIT" queries. |
| core/trino-main/src/main/java/io/trino/sql/planner/optimizations/MetadataQueryOptimizer.java | Introduces and uses new logic to optimize DistinctLimitNode and refactors AggregationNode optimization. |
Comments suppressed due to low confidence (2)
core/trino-main/src/main/java/io/trino/sql/planner/optimizations/MetadataQueryOptimizer.java:127
- [nitpick] Consider renaming the method 'optimize' to 'tryOptimizeTableScan' (or a similar descriptive name) to better communicate that it may not always perform an optimization.
private Optional<ValuesNode> optimize(TableScanNode tableScan)
plugin/trino-iceberg/src/test/java/io/trino/plugin/iceberg/TestMetadataQueryOptimization.java:107
- [nitpick] Consider adding an additional test case that verifies the fallback behavior when the optimization conditions are not met to ensure complete coverage.
assertPlan( format("SELECT DISTINCT b, c FROM %s LIMIT 10", testTable),
kasiafi
approved these changes
Apr 3, 2025
| TableScanNode tableScan = result.get(); | ||
| return findTableScan(node.getSource()) | ||
| .flatMap(this::optimize) | ||
| .map(v -> SimplePlanRewriter.rewriteWith(new Replacer(v), node)) |
| { | ||
| return findTableScan(node.getSource()) | ||
| .flatMap(this::optimize) | ||
| .map(v -> SimplePlanRewriter.rewriteWith(new Replacer(v), node)) |
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Description
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DistinctLimitNodeinMetadataQueryOptimizerAdditional context and related issues
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