Postgres排除重叠时间戳的约束仅在另一列不相等的情况

Question

在Postgres中，我在座位上有一个事件表，这些事件记录了基于事件类型的预订和占领。我想添加第三个约束，该约束可防止一个用户进行预订，而另一个用户同时占用。

到目前为止，我有两个约束，对于每个座位重叠的相同事件，同一用户在不同座位上重叠的事件没有重叠：

CREATE EXTENSION btree_gist;
CREATE TABLE IF NOT EXISTS public.seat_event
(
    id integer NOT NULL GENERATED ALWAYS AS IDENTITY ( INCREMENT 1 START 1 MINVALUE 1 MAXVALUE 2147483647 CACHE 1 ),
    user_id integer references users(id) NOT NULL,
    seat_id integer references area_seat(id) NOT NULL,
    timestamp_range tstzrange,
    event_type text COLLATE pg_catalog."default",
    canceled boolean DEFAULT false,
    PRIMARY KEY (id),
    CONSTRAINT seat_event_overlap EXCLUDE USING gist (
        seat_id WITH =,
        event_type WITH =,
        timestamp_range WITH &&)
        WHERE (not canceled),
    CONSTRAINT event_user_one_seat EXCLUDE USING gist (
        user_id WITH =,
        event_type WITH =,
        timestamp_range WITH &&)
        WHERE (not canceled),
    CONSTRAINT seat_event_one_user EXCLUDE USING gist (
        seat_id WITH =,
        user_id WITH =, -- TODO must be where user is not equal
        timestamp_range WITH &&)
        WHERE (not canceled)
);

我如何在User_id不相同时必须适用排除行为的第三个约束工作？

也许还有一个更优雅的原因，为什么要考虑这些约束？