jnh5y opened a new pull request, #27895:
URL: https://github.com/apache/flink/pull/27895
## What is the purpose of the change
In HyperLogLogPlusPlus.query(), the expression "1 << mIdx" uses int shift
which wraps modulo 32. At high cardinality
(~100M+ distinct values), some registers accumulate values >= 32, causing
the shift to produce incorrect zInverse contributions and wildly wrong
estimates.
## Brief change log
In `HyperLogLogPlusPlus.java`, change "1 << mIdx" to "1L << mIdx" to use
long shift arithmetic.
## Verifying this change
This change added a test in `HyperLogLogPlusPlusTest.java`.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (yes / 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? (no)
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