From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
cc: chris+postgresql@qwirx.com, pgsql-docs@postgresql.org
Subject: Re: SET CONSTRAINTS ALL IMMEDIATE affects SET TRANSACTION READ ONLY
In-reply-to: <d5262e05-5d96-6090-d665-482f036e1717@2ndquadrant.com>
References: <20160909065218.20022.15589@wrigleys.postgresql.org>
 <5491.1473439146@sss.pgh.pa.us>
 <d5262e05-5d96-6090-d665-482f036e1717@2ndquadrant.com>
Comments: In-reply-to Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
	message dated "Mon, 10 Oct 2016 20:47:33 -0400"
Date: Mon, 10 Oct 2016 20:59:11 -0400
Message-ID: <23996.1476147551@sss.pgh.pa.us>
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Sender: pgsql-docs-owner@postgresql.org

Peter Eisentraut <peter.eisentraut@2ndquadrant.com> writes:
> On 9/9/16 12:39 PM, Tom Lane wrote:
>> I wouldn't really imagine that it's sensible to set READ ONLY
>> mid-transaction at all, but if it means anything to do that, surely
>> it ought to mean that no updates can happen *after* you set it.

> I think there is a bit of code missing in check_transaction_read_only().
>  We prevent changing from read-only to read-write after the first query
> but not vice versa.  That seems like an oversight.

The comments around the code make it absolutely clear that it's
intentional, not an "oversight".  Whether it's a good idea is open
for discussion, certainly, but I don't see how you can imagine that
it wasn't considered.

			regards, tom lane


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