From: Tom Lane <tgl@sss.pgh.pa.us>
To: abctevez <swqshapu@163.com>
cc: pgsql-sql@postgresql.org
Subject: Re: does the notification of postgres appear in transaction completed
 order
In-reply-to: <3bc63b9d.f064.1622f0c0a46.Coremail.swqshapu@163.com>
References: <3bc63b9d.f064.1622f0c0a46.Coremail.swqshapu@163.com>
Comments: In-reply-to abctevez <swqshapu@163.com>
	message dated "Fri, 16 Mar 2018 21:42:20 +0800"
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Date: Fri, 16 Mar 2018 10:57:19 -0400
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abctevez <swqshapu@163.com> writes:
> I want to use notify/listen to catch the message that a transaction comp=
leted.Fire notify in trigger and as the official said, it won't notify if =
transaction rollback.However, I am wondering if the message appear in the =
same order with transaction execution.I couldn't find this topic on the of=
ficial web or just I missed it?

https://www.postgresql.org/docs/current/static/sql-notify.html

says

    Except for dropping later instances of duplicate notifications, NOTIFY
    guarantees that notifications from the same transaction get delivered
    in the order they were sent. It is also guaranteed that messages from
    different transactions are delivered in the order in which the
    transactions committed.


			regards, tom lane