[SPARK-50522][SQL] Support for indeterminate collation #49103
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stefankandic
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stefankandic
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@dejankrak-db @stevomitric please take a look, thanks! |
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What changes were proposed in this pull request?
This pull request updates how we handle collation mismatches during
concat,concat_ws, andcollationexpressions. Currently, Spark throws an error for any collation mismatch. This change modifies that behavior by allowing these functions to proceed and return an indeterminate collation instead of failing.However, we should never serialize any data with indeterminate collation, but we can show it back to the user, create views on top of it etc.
If more string functions are identified that don’t depend on collation, they can be easily added to the
canContainIndeterminateCollationmethod and everything should work from that point on.Why are the changes needed?
Throwing errors for all collation mismatches can break queries unnecessarily, especially for functions that don’t rely on collation (like concat). These functions combine strings without needing ordering rules, making collation enforcement unnecessary.
Does this PR introduce any user-facing change?
No.
How was this patch tested?
New unit tests.
Was this patch authored or co-authored using generative AI tooling?
No.