Number of rows in the group (the Count aggregate, issue #1790).
Opaque unique group key - the JSON encoding of path (see
groupPathKey), collision-free even when a model-derived label contains
separator-like characters.
Display label for the group header (this level's value only).
Optionallevel0-based nesting depth (0 = outermost grouping column). Always emitted by
summariseListRows; optional for backward type compatibility.
OptionalpathGroup-by labels from the outermost level down to this group.
columnId → summed numeric value, for the configured sum columns.
One group in a grouped list result. With multi-criteria grouping (issue #1790) groups are emitted as a FLAT pre-order list: each parent group is immediately followed by its subgroups (
levelgives the nesting depth).