postgresql - 将 Postgres 主键类型从 varchar 更改为 uuid 并被其他表引用

Question

我有表客户和用户。我想将他们的 id 从 character varying 更改为 uuid。

=>\d customers;
         Table "public.customers"
  Column  |       Type        | Modifiers
----------+-------------------+-----------
 id       | character varying | not null
 name     | character varying | not null
Indexes:
    "customers_pkey" PRIMARY KEY, btree (id)
    "customers_name_key" UNIQUE CONSTRAINT, btree (name)
Referenced by:
    TABLE "users" CONSTRAINT "users_customer_id_fkey" FOREIGN KEY (customer_id) REFERENCES customers(id) DEFERRABLE INITIALLY DEFERRED

=>\d users;
             Table "public.users"
    Column     |       Type        | Modifiers
---------------+-------------------+-----------
 id            | character varying | not null
 name          | character varying | not null
 customer_id   | character varying | not null
 login         | character varying | not null
Indexes:
    "users_pkey" PRIMARY KEY, btree (id)
    "users_login_key" UNIQUE CONSTRAINT, btree (login)
Foreign-key constraints:
    "users_customer_id_fkey" FOREIGN KEY (customer_id) REFERENCES customers(id) DEFERRABLE INITIALLY DEFERRED

我试过:

=>begin;
set constraints all deferred;
ALTER TABLE users alter customer_id type uuid using customer_id::uuid;
ALTER TABLE customers alter id type uuid using id::uuid;
end;

但是在这一行之后我得到了不兼容的类型错误

=> ALTER TABLE customers alter id type uuid using id::uuid;
ERROR:  foreign key constraint "users_customer_id_fkey" cannot be implemented
DETAIL:  Key columns "customer_id" and "id" are of incompatible types: character varying and uuid.

Answer 1

您肯定想删除外键约束。我很惊讶您不必为 PostgreSQL 删除 PK 约束或索引来更改数据类型。我设置了一个测试，它运行良好，只需要先删除 FK，然后再重新添加它。