apache / apache/datafusion-comet
Support FIRST_VALUE/LAST_VALUE on a RANGE window frame with a literal offset
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area:expressions
enhancement
- Dominant language
- Scala
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Description
`first_value` / `last_value` over a `RANGE` frame that uses a literal `PRECEDING`/`FOLLOWING` offset fall back to Spark today.
See `spark/src/main/scala/org/apache/spark/sql/comet/CometWindowExec.scala` (around lines 404-420), which records "FIRST_VALUE with RANGE frame and literal offset is not supported" / "LAST_VALUE with RANGE frame and literal offset is not supported".
Comet's stateless native RANGE frame cannot reproduce Spark's monotonic lower-bound iterator semantics under non-ANSI overflow, so it falls back rather than risk an incorrect result.
Documented as a current limitation in the window function compatibility guide.
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