Re: todo point: plpgsql - scrollable cursors are supported

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Bruce Momjian <bruce(at)momjian(dot)us>
Subject: Re: todo point: plpgsql - scrollable cursors are supported
Date: 2010-10-07 11:55:42
Message-ID: AANLkTikjVF6bENfxv-et75g-vHnRyy0y0B+og6BprhgQ@mail.gmail.com
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On Thu, Oct 7, 2010 at 7:34 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
> 2010/10/7 Robert Haas <robertmhaas(at)gmail(dot)com>:
>> On Thu, Oct 7, 2010 at 2:38 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>>> 2010/10/7 Robert Haas <robertmhaas(at)gmail(dot)com>:
>>>> On Mon, Oct 4, 2010 at 2:52 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>>>>> I am thinking so you can remove a "scrollable cursor support" from
>>>>> ToDo for plpgsql. Scrollable cursors are supported and supported
>>>>> syntax are same as core SQL language.
>>>>
>>>> I agree, removed.  I also removed WITH HOLD cursors, which we seem to
>>>> have as well.
>>>
>>> I think so we doesn't support WITH HOLD cursor syntax yet. Maybe we
>>> have similar functionality. Don't know.
>>
>> It's in the documentation...
>>
>> http://www.postgresql.org/docs/current/static/sql-declare.html
>
> can be - but it isn't supported by plpgsql. This is similar to
> scrollable cursors - SQL supported it some years, but plpgsql allowed
> it only two years. The minimal necessary change is relative simple
> plpgsql's parser update - but I don't know if there isn't other
> issues.
>
> see http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/gram.y.diff?r1=1.99&r2=1.100

I think the issue there may be that the execution of the function is
wrapped in a transaction anyway, so it's not really clear what WITH
HOLD would do for you. Now, if we could decouple those things... THAT
would be exciting, for a lot more reasons than just this.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company

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