Re: updatable cursors and ORDER BY - Mailing list pgsql-docs

From Peter Eisentraut
Subject Re: updatable cursors and ORDER BY
Date
Msg-id b0af1f4a-b39f-5a18-fcd2-b4f2a4a0303e@2ndquadrant.com
Whole thread Raw
In response to Re: updatable cursors and ORDER BY  (Bruce Momjian <bruce@momjian.us>)
Responses Re: updatable cursors and ORDER BY  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-docs
On 5/28/18 13:17, Bruce Momjian wrote:
> On Thu, May 10, 2018 at 12:55:23PM -0400, Tom Lane wrote:
>> Peter Eisentraut <peter.eisentraut@2ndquadrant.com> writes:
>>> I think that last part isn't actually written down anywhere.  (It only
>>> states the converse.)  How about a clarification like this:
>>
>>> @@ -271,7 +271,10 @@ <title id="sql-declare-notes-title">Notes</title>
>>>       and not use grouping or <literal>ORDER BY</literal>).  Cursors
>>>       that are not simply updatable might work, or might not, depending on plan
>>>       choice details; so in the worst case, an application might work in testing
>>> -     and then fail in production.
>>> +     and then fail in production.  If <literal>FOR UPDATE</literal> is
>>> +     specified, then the cursor is guaranteed to be updatable, or the
>>> +     <command>DECLARE</command> command will error if an updatable cursor
>>> +     cannot be created for the supplied query.
>>>      </para>
>>
>> OK by me, except we don't usually use "error" as a verb.  Either "fail"
>> or "throw an error" would read better IMO.  Or you could just stop with
>> "guaranteed to be updatable"; I don't think the rest adds much.
> 
> I have done as you suggested and just used the first part;  patch
> attached and backpatched.

I think we should still add the second part, because it currently
doesn't say anything about that a cursor declaration might fail if an
updatable cursor cannot be created.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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