Function resolve_sink_layout 

pub(crate) fn resolve_sink_layout(
    output_schema: &[ColumnSchema],
    sink_schema: &[ColumnSchema],
) -> Result<Vec<ColumnSchema>, Error>

Resolves the columns appended by the flow, validating the complete output/sink layout.

A sink with the same arity as the query is an ordinary sink, even when its last column happens to be named update_at. Auto columns are only inferred from the arity difference and their exact trailing layout.