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Re: Updateable cursors patch

From: "FAST PostgreSQL" <fastpgs(at)fast(dot)fujitsu(dot)com(dot)au>
To: pgsql-patches(at)postgresql(dot)org
Subject: Re: Updateable cursors patch
Date: 2007-05-18 08:40:53
Message-ID: 464D6695.4090202@fast.fujitsu.com.au (view raw or flat)
Thread:
Lists: pgsql-patches
Right. The current implementation allows only simple queries. Joins are 
disallowed. According to the standard, updateable cursors cannot be 
scrollable. So maybe I should put an explicit check during cursor 
creation disallowing scrollable updateable cursors.

Rgds,
Arul Shaji


Pavel Stehule wrote:
> 2007/5/18, FAST PostgreSQL <fastpgs(at)fast(dot)fujitsu(dot)com(dot)au>:
>> No. It works with scrollable cursors. It will work for cursors/selects
>> which does not put the results in some store, such as WITH hold/group
>> by/order by etc.... But most of these restrictions apply for normal
>> 'Select for update' anyway. (With the order by clause, the
>> implementation is as per the sql standards.)
> 
> some scrollable cursors are materialised. It depends on query :-(.
> Simple query without join can works.
> 
> regards
> 
> Pavel
> 
>>
>> I can update the documentation once the initial review is done and what
>> I have done gets atleast a pass mark :-)
>>
>> Rgds,
>> Arul Shaji
>>
>>
>> Pavel Stehule wrote:
>> > Hello
>> >
>> > I am not sure, but your solution will faill on scrollable cursors
>> > (it's similar to holdable cursors). I miss part about limits in
>> > documentation. Propably updatable cursors aren't supported by plpgsql
>> > (and it's point to ToDo).
>> >
>> > Regards
>> > Pavel Stehule
>> >
>> > 2007/5/17, FAST PostgreSQL <fastpgs(at)fast(dot)fujitsu(dot)com(dot)au>:
>> >> Attached is an updated version of the updateable cursors patch against
>> >> the latest cvs head.
>> >>
>> >> Most of the changes in the patch are to make it sync with the 
>> changes in
>> >> CVS recently, for DECLARE CURSOR and EXPLAIN, as mentioned by Jaime in
>> >> his mail below.
>> >>
>> >> Rgds,
>> >> Arul Shaji
>> >>
>> >>
>> >> FAST PostgreSQL wrote:
>> >> > Right. I will send an updated patch against the CVS head in the next
>> >> > couple of days.
>> >> >
>> >> > Jaime Casanova wrote:
>> >> >> On 4/4/07, FAST PostgreSQL <fastpgs(at)fast(dot)fujitsu(dot)com(dot)au> wrote:
>> >> >>> Attached is a working updateable cursors patch. The core
>> >> >>> functionality has
>> >> >>> been implemented and the patch also contains the regression 
>> tests and
>> >> >>> documentation.
>> >> >>>
>> >> >>
>> >> >> this one doesn't apply cleanly to HEAD because of the changes in
>> >> >> 
>> http://archives.postgresql.org/pgsql-committers/2007-04/msg00447.php
>> >> >>
>> >> >
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> 


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