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Posted to issues@spark.apache.org by "Nathan Holland (Jira)" <ji...@apache.org> on 2026/08/09 20:01:00 UTC
[jira] [Updated] (SPARK-58677) Expand hash functionalities of XXH3 to better match XXHash64
[ https://issues.apache.org/jira/browse/SPARK-58677?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Nathan Holland updated SPARK-58677:
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Summary: Expand hash functionalities of XXH3 to better match XXHash64 (was: Expand hash functionalities of XXH3)
> Expand hash functionalities of XXH3 to better match XXHash64
> ------------------------------------------------------------
>
> Key: SPARK-58677
> URL: https://issues.apache.org/jira/browse/SPARK-58677
> Project: Spark
> Issue Type: Improvement
> Components: PySpark, SQL
> Affects Versions: 4.4.0
> Reporter: Nathan Holland
> Priority: Major
>
> This ticket expands on SPARK-45900, to explicitly mention the desire for a BINARY return type for xxhash3_128 as well as additional functionality that a modern hashing algorithm on Spark could implement. (such as deterministic support for complex types)
> The original intent of that ticket was to capture a new hashing model through XXH3 that allowed for high performance hashing using XXH3 with the API of the earlier XXHash64 hash family, rather than some of the cryptographic hash functions (SHA/MD5 etc)
> One difference in this model I am proposing - SPARK-45900 has been resolved by returning a string, which is more consistent with the older hashing models. When writing SPARK-45900 I mentioned that this was a downside of the existing SHA models, to clarifify - returning a STRING type has heavier overhead and prevents future optimisations that occur by allowing HotSpot (and C interpreters like Photon) to take advantage of SIMD instructions. Furthermore I've been experimenting with expanding the BINARY type to have fixed byte types and have seen some promising performance increases that may be useful at a later date.
> As XXH3 was built specifically around SIMD instructions to provide speed ups over XXHash64 and Spark 4.4 is not out yet, I believe now would be the time to discuss what this API should return - and either choose with a seperate API that returns the BINARY 128 bytes or make the change to the solution of SPARK-45900 to return a BINARY type by default and let users use the "hex" function if they want the result as a Binary String.
> I have heard from customers that one of xxhash64's benefits is the simple API to support multiple columns which conceptually allow the hashing of columns by passing them in natively without having to implement brittle solutions (often something like concat_ws) to hash data. I believe an expansion to the functionality to SPARK-45900 to support columns would allow XXH3 to be seen successor to the XXHash64 function with this user friendly API - while keeping all the semantics that a unitary function would support - including byte compatability with the original C reference code.
> My current codebase can be found here for a proposed implementation of the above two key changes (better support for hashing data types and multiple columns, and the return of a binary type which better captures the hash results rather than a string)
> * [https://github.com/NathanNZ/spark/commit/d4317b9853a9b1f775c1ab11534dc8ea5a048040]
> * I've also got a work in progress solution with pre-built containers to test the functionality.
> ** [https://github.com/NathanNZ/spark-nathan-containers]
> Links:
> - https://issues.apache.org/jira/browse/SPARK-45900 (Original SPARK-45900 ticket)
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