Function build_success_response 

fn build_success_response(
    kind: &MutationKind,
    returning: &[MirScalarExpr],
    diffs: &[(Row, Diff)],
    max_result_size: u64,
    max_query_result_size: u64,
    row_set_finishing_seconds: &Histogram,
) -> Result<ExecuteResponse, AdapterError>

Builds the response for a write that is about to be submitted.

This runs before the write, so the result-size checks in here reject the statement without having written anything.