add note about expression compatibility

andygrove · andygrove · commit cafb5583b0e2 · 2025-11-19T10:24:13.000-07:00
diff --git a/docs/source/contributor-guide/adding_a_new_operator.md b/docs/source/contributor-guide/adding_a_new_operator.md
@@ -181,6 +181,8 @@ Support levels:
 - **`Incompatible()`** - Supported but may differ; requires explicit opt-in
 - **`Unsupported()`** - Not supported under current conditions
 
+Note that Comet will treat an operator as incompatible if any of the child expressions are incompatible.
+
 ### Step 3: Register the Operator
 
 Add your operator to the `opSerdeMap` in `QueryPlanSerde.scala`:
