Comet supports ROWS and RANGE window frame units but not GROUPS.
The proto enum only defines Rows and Range (native/proto/src/proto/operator.proto, WindowFrameType), and the native planner has explicit guards that return "WindowFrameUnits::Groups is not supported." (native/core/src/execution/planner.rs, in create_window_expr).
Spark supports GROUPS frames, so queries using them fall back to Spark. Adding support means extending the proto enum, the Scala serde in CometWindowExec.scala, and the native frame construction in planner.rs.
Documented as a current limitation in the window function compatibility guide.
Comet supports
ROWSandRANGEwindow frame units but notGROUPS.The proto enum only defines
RowsandRange(native/proto/src/proto/operator.proto,WindowFrameType), and the native planner has explicit guards that return "WindowFrameUnits::Groups is not supported." (native/core/src/execution/planner.rs, increate_window_expr).Spark supports
GROUPSframes, so queries using them fall back to Spark. Adding support means extending the proto enum, the Scala serde inCometWindowExec.scala, and the native frame construction inplanner.rs.Documented as a current limitation in the window function compatibility guide.