SmirAlex opened a new pull request, #22351:
URL: https://github.com/apache/flink/pull/22351
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## What is the purpose of the change
This pull request adds a support of emitting UPDATE_BEFORE and UPDATE_AFTER
records in streaming LEFT/RIGHT/FULL OTHER JOIN. Previously, we explicitly was
changing RowKind of output records to INSERT/DELETE for simplicity. Emitting
UPDATE_BEFORE/UPDATE_AFTER records can be considered as on optimization in case
when we have an UPSERT stream (without UPDATE_BEFORE).
Additionally, this pull request closes the bug
https://issues.apache.org/jira/browse/FLINK-31729 (unexpected UPDATE_BEFORE
record with subsequent INSERT record), because it won't be present with the new
logic.
## Brief change log
- Refactor method StreamingJoinOperator#processElement to support emitting
UPDATE_BEFORE/UPDATE_AFTER records
- New logic: Forward input RowKind in all join kinds and, additionally,
for outer join explicitly set -U & +U to retract / emit rows with null other
side
- Code was shortened and simplified
- Update pseudo-code above refactored method
## Verifying this change
Existing tests:
- org.apache.flink.table.planner.runtime.stream.sql.JoinITCase
As previously there were no unit tests on `StreamingJoinOperator` (there
were only IT cases), it was decided to write a test class that covers already
present logic as well - `StreamingJoinOperatorTest`.
This change added tests and can be verified as follows:
- Test for inner join with unique join key (it just forward input RowKind)
- Test for inner join with non-unique join key (can be multiple associated
records from other side by specific key)
- Test for left outer join with unique join key (forwards input RowKind
and -U/+U in case of null non-outer side)
- Test for left outer join with non-unique join key (-//- + can be
multiple associated records from other side by specific key)
- Test for full outer join with unique join key (forwards input RowKind
and -U/+U in case of null left/right side)
## 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): (yes)
- 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? (no)
- If yes, how is the feature documented? (not applicable)
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