docs: document negative zero cast-to-string incompatibility#3811
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andygrove merged 2 commits intoapache:mainfrom Mar 27, 2026
Merged
docs: document negative zero cast-to-string incompatibility#3811andygrove merged 2 commits intoapache:mainfrom
andygrove merged 2 commits intoapache:mainfrom
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Add tracking issue links to Incompatible() declarations that were missing them for ArraysOverlap, ArrayUnion, and TimestampNTZ casts.
Document in the compatibility guide that casting floating-point negative zero to string may produce "-0.0" in Comet instead of "0.0" as in Spark. This is a minor edge case since -0.0 and 0.0 are semantically equivalent in IEEE 754. Closes apache#1036
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Which issue does this PR close?
Closes #1036
Rationale for this change
When casting floating-point negative zero (
-0.0) to string, Spark normalizes it to"0.0"but Comet produces"-0.0". Rather than fixing this edge case (which involves complexities deep in the native execution pipeline), we document it in the compatibility guide since negative zero and positive zero are semantically equivalent in IEEE 754.What changes are included in this PR?
Adds a "Negative Zero" subsection under the Cast section of the compatibility guide explaining this behavior difference and linking to the tracking issue.
How are these changes tested?
Documentation-only change.