PostgreSQL 为所有外键添加“删除级联”

Question

我正在寻找一种方法将

on delete cascade

添加到我的 PostgreSQL 数据库中的所有外键（最好仅限于模式）。我找到了一个脚本here，但它似乎不适用于 PostgreSQL。该解决方案不必使用脚本，GUI 工具也可以。

谢谢你。

Answer 1

建议和支持的方法是添加具有相同定义和

ON DELETE CASCADE

的新约束，然后删除原始约束。

如果您准备好冒险通过目录修改来破坏数据库，并且您信任来自互联网的随机 SQL 语句，您可以尝试

WITH tables(oid) AS (
   UPDATE pg_constraint
   SET confdeltype = 'c'
   WHERE contype = 'f'
     AND confdeltype <> 'c'
     AND connamespace = 'myschema'::regnamespace
   RETURNING confrelid
)
UPDATE pg_trigger
SET tgfoid = '"RI_FKey_cascade_del"()'::regprocedure
FROM tables
WHERE tables.oid = pg_trigger.tgrelid
  AND tgtype = 9;

使用前请先测试！

Answer 2

无需更改数据库目录，此函数应该以一种不那么可怕的方式完成任务。

create function "UpdateAllForeignKeys"(on_delete varchar)
returns void
language plpgsql
as
    $$
declare
    rec record;
    drop_statement varchar;
    add_statement varchar;
begin
for rec in
    select
        tc.table_schema,
        tc.constraint_name,
        tc.table_name,
        kcu.column_name,
        ccu.table_schema as foreign_table_schema,
        ccu.table_name as foreign_table_name,
        ccu.column_name as foreign_column_name
    from information_schema.table_constraints as tc
    join information_schema.key_column_usage as kcu
        on tc.constraint_name = kcu.constraint_name
        and tc.table_schema = kcu.table_schema
    join information_schema.constraint_column_usage as ccu
        on ccu.constraint_name = tc.constraint_name
        where tc.constraint_type = 'FOREIGN KEY'
        and tc.table_schema = 'my_schema'
        and ccu.table_schema = 'my_foreign_schema'
    LOOP
        execute 'alter table only ' || rec.table_schema || '.' || rec.table_name || ' drop constraint ' || rec.constraint_name || ';';
        execute 'alter table only ' || rec.table_schema || '.' || rec.table_name || ' add constraint ' || rec.constraint_name || ' foreign key (' || rec.column_name || ') references ' || rec.foreign_table_schema || '.' || rec.foreign_table_name || ' (' || rec.foreign_column_name || ') on delete ' || on_delete || ';';
    end loop;
end;
$$;

select "UpdateAllForeignKeys"('cascade');