我在postgres USER表上应用了unique constraint，而在email上应用了unique constraint，我现在面临的问题是，约束似乎注册了我插入（或尝试插入）的每个值，而不管具有该值的记录是否存在。
表格：
| 身份证|用户|
| - ------|- ------|
| 1个|www.example.commail@gmail.com|
| 第二章|www.example.commail2@gmail.com|
如果我插入www.example.com，请删除该值，然后尝试再次插入mail3@gmail.com，它将显示：mail3@gmail.com, delete the value and try to insert mail3@gmail.com again it says:
sqlalchemy.exc.IntegrityError:（psycopg2.errors.UniqueViolation）重复的键值违反了唯一约束"email"
我的怀疑是：唯一约束保证值总是较新的，或者在列中只有该值的一个记录？
文件上说是第二个，但经验表明是第一个
更多详情：

|      Column      |            Type             | Nullable |
|------------------|-----------------------------|----------|
| id               | integer                     | not null |
| email            | character varying(100)      |          |
| password         | character varying(100)      |          |
| name             | character varying(1000)     |          |
| lastname         | character varying(1000)     |          |
| dni              | character varying(20)       |          |
| cellphone        | character varying(20)       |          |
| accepted_terms   | boolean                     |          |
| investor_test    | boolean                     |          |
| validated_email  | boolean                     |          |
| validated_cel    | boolean                     |          |
| last_login_at    | timestamp without time zone |          |
| current_login_at | timestamp without time zone |          |
| last_login_ip    | character varying(100)      |          |
| current_login_ip | character varying(100)      |          |
| login_count      | integer                     |          |
| active           | boolean                     |          |
| fs_uniquifier    | character varying(255)      | not null | 
| confirmed_at     | timestamp without time zone |          |

Indexes:
    "bondusers_pkey" PRIMARY KEY, btree (id)
    "bondusers_email_key" UNIQUE CONSTRAINT, btree (email)
    "bondusers_fs_uniquifier_key" UNIQUE CONSTRAINT, btree (fs_uniquifier)

插入声明：

INSERT INTO bondusers (email, password, name, lastname, dni, cellphone, accepted_terms, investor_test, validated_email, validated_cel, last_login_at, current_login_at, last_login_ip, current_login_ip, login_count, active, fs_uniquifier, confirmed_at) VALUES ('mail3@gmail.com', '$pbkdf2-sha256$29000$XyvlfI8x5vwfYwyhtBYi5A$Hhfrzvqs94MjTCmDOVmmnbUyf7ho4kLEY8UYUCdHPgM', 'mail', 'mail3', '123123123', '1139199196', false, false, false, false, NULL, NULL, NULL, NULL, NULL, true, '1c4e60b34a5641f4b560f8fd1d45872c', NULL);

ERROR:  duplicate key value violates unique constraint "bondusers_fs_uniquifier_key"
DETAIL:  Key (fs_uniquifier)=(1c4e60b34a5641f4b560f8fd1d45872c) already exists.

但当：

select * from bondusers where fs_uniquifier = '1c4e60b34a5641f4b560f8fd1d45872c';

结果为0行