chore: remove unused spark.comet.exceptionOnDatetimeRebase config - #5221
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andygrove merged 1 commit intoAug 2, 2026
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This config was never read anywhere in the codebase. Setting it had no effect: Comet never raised on dates/timestamps written with the legacy hybrid Julian/Gregorian calendar. Remove the dead config and drop the note about it from the Parquet scan compatibility guide, which already documents the underlying lack of datetime rebasing support (apache#5010).
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Which issue does this PR close?
Related to #5010.
Rationale for this change
spark.comet.exceptionOnDatetimeRebaseis declared inCometConfbut is never read anywhere in the codebase — JVM or native. Setting it totruehad no effect: Comet did not raise on dates/timestamps written with the legacy hybrid (Julian + Gregorian) calendar, it silently read them as Proleptic Gregorian. The config therefore advertised a safety guard that does not exist, which is worse than not offering one at all.The real gap — no datetime rebasing in the native Parquet scan — is tracked by #5010 and remains documented in the scan compatibility guide.
What changes are included in this PR?
COMET_EXCEPTION_ON_LEGACY_DATE_TIMESTAMP/spark.comet.exceptionOnDatetimeRebasefromCometConf.scala.docs/source/user-guide/latest/compatibility/scans.mdthat called out the config as dead code. The surrounding paragraph already describes the missing rebasing support and links to Datetime rebase: track the documented scan limitation, and spark.comet.exceptionOnDatetimeRebase is dead code #5010.No upgrade guide entry is added: removing the key is not a behavior change, since no code path ever consulted it, and Spark ignores unrecognized
spark.comet.*keys that users may still have set.How are these changes tested?
Nothing referenced the config, so there is no behavior to test. Verified with a repo-wide grep for both the key string and the Scala symbol (only the two edited sites matched) and confirmed
common+sparkcompile cleanly.