DO $$
DECLARE
    bns CURSOR FOR SELECT * FROM waterway.bottlenecks FOR UPDATE;
    call_stack text;
BEGIN
    FOR cur_bn IN bns LOOP
        BEGIN
            UPDATE waterway.bottlenecks bn SET area = ISRSrange_area(
                ISRSrange_axis(stretch,
                    COALESCE((
                        -- Guess tolerance from the last successful
                        -- bottleneck import owned by a waterway_admin of
                        -- the country matching the bottleneck_id
                        SELECT DISTINCT ON (usr.country)
                                CAST(substring(msg FROM '((\d*\.)?\d+)$')
                                    AS float)
                            FROM import.import_logs log
                                JOIN import.imports imp
                                    ON log.import_id = imp.id
                                JOIN users.list_users usr USING (username)
                            WHERE starts_with(log.msg,
                                    'Tolerance used to snap waterway axis:')
                                AND imp.kind = 'bn'
                                AND imp.state IN('accepted', 'reviewed')
                                AND usr.rolname = 'waterway_admin'
                                AND usr.country = substring(
                                    bn.bottleneck_id FROM 1 FOR 2)
                            ORDER BY usr.country, imp.changed DESC),
                        -- Use default tolerance if originally used cannot
                        -- be determined
                        5)),
                (SELECT ST_Collect(CAST(area AS geometry))
                    FROM waterway.waterway_area))
            WHERE CURRENT OF bns;
        EXCEPTION
            WHEN no_data_found THEN
                GET STACKED DIAGNOSTICS call_stack = PG_EXCEPTION_CONTEXT;
                RAISE WARNING '% (%): %, CONTEXT: %',
                    cur_bn.bottleneck_id, cur_bn.validity,
                    SQLERRM, call_stack;
        END;
    END LOOP;
END $$;