jiangxt2 commented on PR #58066:
URL: https://github.com/apache/spark/pull/58066#issuecomment-5339562501

   Additional ecosystem references:
   
   For reference, the same four bitmap set operations are also available in 
several analytical SQL engines:
   
   - [Flink 
2.3](https://nightlies.apache.org/flink/flink-docs-release-2.3/docs/sql/functions/built-in-functions/#bitmap-functions)
 exposes `BITMAP_AND`, `BITMAP_OR`, `BITMAP_ANDNOT`, and `BITMAP_XOR` over its 
native `BITMAP` type.
   - 
[ClickHouse](https://clickhouse.com/docs/reference/functions/regular-functions/bitmap-functions)
 has provided `bitmapAnd`, `bitmapOr`, `bitmapAndnot`, and `bitmapXor` since 
v20.1.
   - Apache Doris provides `BITMAP_AND`, `BITMAP_OR`, `BITMAP_AND_NOT`, and 
`BITMAP_XOR`, and documents bitmap use cases such as [exact distinct counting 
and audience 
segmentation](https://doris.apache.org/docs/4.x/query-acceleration/distinct-counts/bitmap-precise-deduplication/).
   - [StarRocks](https://docs.starrocks.io/docs/category/bitmap/) provides the 
corresponding `bitmap_and`, `bitmap_or`, `bitmap_andnot`, and `bitmap_xor` 
functions and documents bitmap use cases such as exact distinct counting and 
retention analysis.
   
   These engines use different physical bitmap representations, so this 
comparison does not imply binary-format compatibility. Spark continues to use 
its existing 4096-byte `BINARY` flat bitmap, and both operands must use the 
same bit-position mapping and, when bucketed, represent the same bucket.
   
   These ecosystem references support the completeness and naming of the 
proposed API. The four scalar functions allow users to compute row-wise 
intersection, union, difference, and symmetric difference between precomputed 
bitmaps without implementing equivalent UDFs.


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