Fix ClassCastException in PPL multisearch on indexes with @timestamp alias field#5577
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Pull request overview
This PR fixes a Calcite planning/runtime ClassCastException triggered by | multisearch on indices where @timestamp is a field-type alias. The fix corrects collation trait handling on scan nodes so the collation trait is replaced (not composed) during sort/project pushdown.
Changes:
- Replace
RelTraitSet.plus(RelCollations.of(...))withRelTraitSet.replace(RelCollations.of(...))in sort pushdown to avoid creatingRelCompositeTrait. - Replace
RelTraitSet.plus(...)withreplace(...)when reindexing collations after project pushdown. - Add an integration regression test covering multisearch against an index with an alias-mapped
@timestamp.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| opensearch/src/main/java/org/opensearch/sql/opensearch/storage/scan/CalciteLogicalIndexScan.java | Uses RelTraitSet.replace() when reindexing collations after project pushdown. |
| opensearch/src/main/java/org/opensearch/sql/opensearch/storage/scan/AbstractCalciteIndexScan.java | Uses RelTraitSet.replace() when setting collations during sort pushdown. |
| integ-test/src/test/java/org/opensearch/sql/calcite/remote/CalciteMultisearchCommandIT.java | Adds regression IT for multisearch on an index where @timestamp is an alias field. |
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@gingeekrishna thanks for taking care of this issue, could you please check CI failures? |
…alias field Fixes opensearch-project#5533. When `@timestamp` is defined as a field-type alias in the index mapping, multisearch queries threw: ClassCastException: RelCompositeTrait cannot be cast to RelCollation Root cause: `reIndexCollations()` in `CalciteLogicalIndexScan` and `pushDownSort()` in `AbstractCalciteIndexScan` both called `RelTraitSet.plus()` to update the collation trait on a scan node. `plus()` *composes* traits — if the trait set already contains a `RelCollation`, it merges the old and new collations into a `RelCompositeTrait`. Calcite's `RelTraitSet.getCollation()` then does an unchecked cast `(RelCollation) getTrait(...)` which fails at runtime for `RelCompositeTrait`. The `@timestamp` alias path specifically triggers this because `wrapProjectForAliasFields()` adds a project on top of each sub-scan which is later pushed back down via `pushDownProject()`. `pushDownProject()` calls `reIndexCollations()` to remap field indices inside an existing collation — but re-using `plus()` here composes the existing sort collation with the re-indexed one, producing the bad composite. Fix: use `RelTraitSet.replace()` in both locations. `replace()` substitutes the collation trait in-place regardless of what was there before, which is the correct semantics for "this scan is now sorted by these columns". Added a regression IT (`testMultisearchWithTimestampAliasFieldDoesNotThrow`) that runs a multisearch against `TEST_INDEX_ALIAS`, whose mapping defines `@timestamp` as an alias for `original_date`. Signed-off-by: Radhakrishnan Pachyappan <gingeekrishna@gmail.com>
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Summary
Fixes #5533.
When
@timestampis defined as a field-type alias in the index mapping (e.g."@timestamp": {"type": "alias", "path": "timestamp"}), running a| multisearchcommand on that index throws:Root cause
reIndexCollations()(CalciteLogicalIndexScan) andpushDownSort()(AbstractCalciteIndexScan) both calledRelTraitSet.plus()to set the collation trait on a scan node.plus()composes traits — when the trait set already contains aRelCollation, it merges the old and new collations into aRelCompositeTrait. Calcite'sRelTraitSet.getCollation()then does an unchecked cast(RelCollation) getTrait(...)which fails at runtime forRelCompositeTrait.The
@timestampalias path specifically triggers this becausewrapProjectForAliasFields()adds aLogicalProjecton top of each sub-scan during multisearch plan building. Calcite's push-down rules later push this project back into the scan viapushDownProject()→reIndexCollations(), which usesplus()to remap an existing sort collation — producing the bad composite trait.Fix
Use
RelTraitSet.replace()in both locations instead ofplus().replace()substitutes the collation trait in-place regardless of what was already there, which is the correct semantics for "this scan is sorted by these columns".Files changed (3):
opensearch/.../AbstractCalciteIndexScan.java—pushDownSort():plus→replaceopensearch/.../CalciteLogicalIndexScan.java—reIndexCollations():plus→replaceinteg-test/.../CalciteMultisearchCommandIT.java— regression IT againstTEST_INDEX_ALIAS(which maps@timestampas a field-type alias tooriginal_date)Test plan
testMultisearchWithTimestampAliasFieldDoesNotThrowIT — runs a multisearch against an index where@timestampis a field-type alias; this would have crashed withClassCastExceptionbefore this fixCalciteMultisearchCommandITtests passOpenSearchIndexScanOptimizationTestand related unit tests pass (.replace()is correct semantics here — a scan's collation is always a full replacement, never a union of multiple sort orders)Checklist
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.