Re: Scrolling/Updating Cursors

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От Kevin Wooten
Тема Re: Scrolling/Updating Cursors
Дата
Msg-id 49897DD1-F979-43C0-9667-312CEA8807FF@me.com
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Ответ на Re: Scrolling/Updating Cursors  (John Meyer <johnmeyer@pueblocomputing.com>)
Список pgsql-general
On Nov 22, 2013, at 2:32 PM, John Meyer <johnmeyer@pueblocomputing.com> wrote:

> Why not both?  I keep on searching even when I post up a question.
>

Just attempting to be polite and not cross post to too much. I have pretty much exhausted my own search and now am
relyingon the kindness and knowledge of others ;) 

> On 11/22/2013 2:27 PM, Kevin Wooten wrote:
>> On Nov 19, 2013, at 6:33 PM, Kevin Wooten <kdubb@me.com> wrote:
>>
>>> My apologies for posting what is almost certainly somewhat of a repeat question but I have searched and attempted
everythingI can think of and cannot figure it out myself. 
>>>
>>> The basic question is… Is it possible to get a scrollable cursor that, within a transaction, can
insert/update/deleterows and see those changes? 
>>>
>>> Why you ask? Because I am implementing the JDBC 4.1 spec and it (optionally) provides this ability and I’d like to
provideit if possible.  I thought just using a scrollable cursor with the isolation-level set to repeatable-read would
dothe trick but it still seems to see no changes (inserts/updates/deletes). 
>>>
>>> Effectively I want roughly this sequence of events to work.
>>>
>>> CREATE TABLE test (val text);
>>>
>>> BEGIN;  # Could include ISOLATION LEVEL REPEATABLE READ
>>>
>>> DECLARE c1 CURSOR FOR SELECT * FROM test;
>>>
>>> FETCH ABSOLUTE 1;     # Returns No Row
>>>
>>> INSERT INTO test VALUES (‘1');
>>> INSERT INTO test VALUES (‘2');
>>> INSERT INTO test VALUES (‘3');
>>>
>>> FETCH ABSOLUTE 1;  # Returns “1”
>>> FETCH NEXT:               # Returns “2"
>>> DELETE FROM test WHERE CURRENT OF c1;  # Deletes “2”
>>>
>>> FETCH ABSOLUTE 1;  # Returns “1”
>>> FETCH NEXT;               # Returns “3”
>>> UPDATE test SET val=‘4' WHERE CURRENT OF c1;
>>> FETCH RELATIVE 0;    # Returns “4”
>>>
>>> COMMIT;
>>>
>>> Thanks!
>>>
>>> -kw
>>>
>>
>> Should I take silence to mean this cannot be done?  Or should I send to -hackers?
>>
>>
>>



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