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branch-4.1:[fix](mtmv) Avoid invalid slot cast in MV null-reject compensation (#66613) - #67266

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branch-4.1:[fix](mtmv) Avoid invalid slot cast in MV null-reject compensation (#66613)#67266
yiguolei merged 1 commit into
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@seawinde

@seawindeseawinde commented Aug 28, 2026

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pr: #66613
commitId: a97548f

@seawinde
[fix](mtmv) Avoid invalid slot cast in MV null-reject compensation (a…
a97548f
…pache#66613)
### What problem does this PR solve?
Related PR: apache#43539, apache#62492, apache#63268
Problem Summary:
When an INNER JOIN query is matched against a LEFT OUTER JOIN materialized
view, the rewrite must prove that the nullable side is null-rejected. The MV
rule shuttles the nullable-side output Slots through the view plan lineage to
normalize Project and Alias outputs before selecting an `IS NOT NULL`
compensation Slot.
`AbstractMaterializedViewRule.getShuttledRequireNoNullableViewSlots()` assumed
that `ExpressionUtils.shuttleExpressionWithLineage()` always returns `Slot`
values and unconditionally used `Slot.class::cast`. The API returns general
`Expression` values. Expression JOIN keys such as CAST equality can introduce
helper projections whose lineage expands to `Cast`, causing a
`ClassCastException` during MV rewrite.
This is a conservative crash fix, not transparent rewrite support for CAST or
arbitrary derived expressions. If no usable Slot remains after lineage
expansion, the existing proof checks return invalid and the MV rewrite safely
falls back to base tables.
### Release note
Fixed an internal `ClassCastException` during materialized view rewrite for
expression-based join keys. Unsupported derived-expression lineage now falls
back safely.
### Check List (For Author)
- Test: Unit Test
- `NullRejectInferenceTest`
- Behavior changed: Yes, unsupported derived-expression lineage falls back instead of throwing
- Does this need documentation: No
@hello-stephen

hello-stephen commented Aug 28, 2026

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Thank you for your contribution to Apache Doris.
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Please clearly describe your PR:

  1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
  2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
  3. What features were added. Why was this function added?
  4. Which code was refactored and why was this part of the code refactored?
  5. Which functions were optimized and what is the difference before and after the optimization?

@seawinde

seawinde commented Aug 28, 2026

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run buildall

@yiguolei
yiguolei merged commit 1d465f6 into apache:branch-4.1Aug 28, 2026
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3 participants

@seawinde@hello-stephen@yiguolei