fhueske opened a new pull request, #29421:
URL: https://github.com/apache/flink/pull/29421
## What is the purpose of the change
LATERAL SNAPSHOT join required at least one equality predicate and rejected
any join without one. This also rejected valid equi-joins whose equi-key was
folded to a constant by a local filter on the join key (e.g. `ON o.k = c.k
WHERE o.k = 'x'`): Calcite pins both sides to the constant and simplifies the
join condition, leaving no equi-key for the rule to find.
Lift the equi-key requirement so LATERAL SNAPSHOT behaves like other Flink
joins that tolerate a missing equi-key: a keyless join runs single-threaded -
SINGLETON distribution in streaming (the operator already supports an empty
key) and a broadcast nested-loop join in batch. A join with an equi-key is
unchanged.
This resolves FLINK-40902: the filtered query above now plans and executes
correctly instead of being rejected.
## Brief change log
* prod changes
* remove equi-join predicate check from optimizer rule
* add logic to translate batch LSJ into broadcast NL join if there's no
equi-join predicate
* tests
* add operator harness tests to ensure that operator runs correctly in
keyless setting
* add stream + batch compiler tests to ensure statements are correctly
planned
* add semantic tests to ensure correct e2e execution
* update docs: remove equi-join restriction
## Verifying this change
* run existing and new LSJ tests
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): no
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: no
- The serializers: no
- The runtime per-record code paths (performance sensitive): no
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
- The S3 file system connector: no
## Documentation
- Does this pull request introduce a new feature? yes
- If yes, how is the feature documented? docs
---
##### Was generative AI tooling used to co-author this PR?
- [X] Yes (please specify the tool below)
Generated-by: Claude Code (Claude Opus 4.8)
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