如何检查PostgreSQL中是否存在触发器？ [英] How to check if trigger exists in PostgreSQL?

问题描述

我想验证数据库迁移的正确性，该迁移将触发器添加到某些表中。我使用的是 sqitch ，所以我想找到一种使用SQL查询进行检查的方法。我相信postgres系统表应该可以，但是我目前找不到解决方法。

I want to verify correctness of database migrations which add triggers to some tables. I'm using sqitch, so I'd like to find a way to check it with SQL queries. I believe it should be possible with postgres system tables, but I currently can't find a way to do this.

推荐答案

使用目录 pg_trigger 。

对表书籍的简单查找：

select tgname
from pg_trigger
where not tgisinternal
and tgrelid = 'books'::regclass;

    tgname     
---------------
 books_trigger
(1 row)

使用 pg_proc 来获取触发函数的来源：

Using pg_proc to get the source of the trigger function:

select tgname, proname, prosrc 
from pg_trigger
join pg_proc p on p.oid = tgfoid
where not tgisinternal
and tgrelid = 'books'::regclass;

    tgname     |    proname    |                    prosrc
---------------+---------------+------------------------------------------------
 books_trigger | books_trigger |                                               +
               |               | begin                                         +
               |               |     if tg_op = 'UPDATE' then                  +
               |               |         if new.listorder > old.listorder then +
               |               |             update books                      +
               |               |             set listorder = listorder- 1      +
               |               |             where listorder <= new.listorder  +
               |               |             and listorder > old.listorder     +
               |               |             and id <> new.id;                 +
               |               |         else                                  +
               |               |             update books                      +
               |               |             set listorder = listorder+ 1      +
               |               |             where listorder >= new.listorder  +
               |               |             and listorder < old.listorder     +
               |               |             and id <> new.id;                 +
               |               |             end if;                           +
               |               |     else                                      +
               |               |         update books                          +
               |               |         set listorder = listorder+ 1          +
               |               |         where listorder >= new.listorder      +
               |               |         and id <> new.id;                     +
               |               |     end if;                                   +
               |               |     return new;                               +
               |               | end
(1 row)

pg_get_triggerdef（） 函数用法：

Example of the pg_get_triggerdef() function usage:

select pg_get_triggerdef(t.oid) as "trigger declaration"
from pg_trigger t
where not tgisinternal
and tgrelid = 'books'::regclass;

                                             trigger declaration                
--------------------------------------------------------------------------------------------------------------
 CREATE TRIGGER books_trigger BEFORE INSERT OR UPDATE ON books FOR EACH ROW EXECUTE PROCEDURE books_trigger()
(1 row) 

在Sqitch verify 脚本中您可以使用匿名代码块，例如：

In a Sqitch verify script you can use an anonymous code block, e.g.:

do $$
begin
    perform tgname
    from pg_trigger
    where not tgisinternal
    and tgrelid = 'books'::regclass;
    if not found then 
        raise exception 'trigger not found';
    end if;
end $$;

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