[jira] [Resolved] (SPARK-57924) Add bitmap_xor_agg aggregation function

["jiangxintong (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-57924?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

jiangxintong resolved SPARK-57924.
----------------------------------
    Resolution: Abandoned

> Add bitmap_xor_agg aggregation function
> ---------------------------------------
>
>                 Key: SPARK-57924
>                 URL: https://issues.apache.org/jira/browse/SPARK-57924
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 4.2.0
>            Reporter: jiangxintong
>            Priority: Major
>              Labels: pull-request-available
>
> Introduce bitmap_xor_agg, a bitwise XOR (symmetric difference) aggregation function for flat bitmaps, completing the function set alongside bitmap_or_agg (3.5.0), bitmap_construct_agg (3.5.0), bitmap_count (3.5.0), and bitmap_and_agg (4.1.0, SPARK-53877).
> The bitmap_xor_agg function outputs a bitmap representing the bitwise XOR of all bitmaps in the input column. The input column must contain bitmaps generated from bitmap_construct_agg().
> {code:sql}
> > SELECT substring(hex(bitmap_xor_agg(col)), 0, 6) FROM VALUES (X '10'), (X '30'), (X '40') AS tab(col);
>  600000
> > SELECT substring(hex(bitmap_xor_agg(col)), 0, 6) FROM VALUES (X '10'), (X '10') AS tab(col);
>  000000
> {code}
> (The second example demonstrates symmetric difference: two identical values XOR to zero.)
> h2. Use Cases
> Symmetric difference is useful for:
>  * Finding users who belong to exactly one of two groups (not both)
>  * Detecting changes between two snapshots
>  * Any scenario requiring XOR semantics on bitmaps
> h2. Implementation
> Follow the exact pattern of BitmapAndAgg (SPARK-53877):
>  * Merge operation: buffer[i] ^= input[i]
>  * Initialize buffer to all zeros (same as BitmapOrAgg)
>  * Both update() and merge() paths must use XOR
> Relates to: SPARK-53877



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