From: Tom Lane <tgl@sss.pgh.pa.us>
To: Laurenz Albe <laurenz.albe@cybertec.at>
cc: Haribabu Kommi <kommi.haribabu@gmail.com>,
        Robert Haas <robertmhaas@gmail.com>,
 Jing Wang <jingwangian@gmail.com>,
        Pg Hackers <pgsql-hackers@postgresql.org>,
        "Tsunakawa,
    Takayuki" <tsunakawa.takay@jp.fujitsu.com>
Subject: Re: Libpq support to connect to standby server as priority
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Comments: In-reply-to Laurenz Albe <laurenz.albe@cybertec.at>
	message dated "Fri, 09 Nov 2018 12:53:01 +0100"
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Date: Mon, 12 Nov 2018 13:23:32 -0500
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Laurenz Albe <laurenz.albe@cybertec.at> writes:
> Haribabu Kommi wrote:
>> Added comments along the lines that you mentioned. And also try
>> to update some more comments.

> Looks ok to me, I'll mark it as "ready for committer".

I don't like this patch at all: the business with keeping two connections
open seems impossibly fragile and full of race conditions.  (For instance,
by the time you return the read-only session to the application, it might
not be read-only any more.  I also wonder what inquiry functions like
PQsocket ought to return while in this state.)  I think the feature
definition needs to be re-thought to make that unnecessary.

Also, we really need to consider the interaction between this and the
feature(s) being discussed in the thread at

https://www.postgresql.org/message-id/flat/1700970.cRWpxnom9y%40hammer.mag=
icstack.net

			regards, tom lane