Message-ID: <4721F33F.10704@4js.com>
Date: Fri, 26 Oct 2007 16:01:35 +0200
From: Sebastien FLAESCH <sf@4js.com>
Organization: Four J's Development Tools
User-Agent: Thunderbird 1.5.0.9 (X11/20061220)
MIME-Version: 1.0
To: Sebastien FLAESCH <sf@4js.com>
CC: Tom Lane <tgl@sss.pgh.pa.us>,
 Heikki Linnakangas <heikki@enterprisedb.com>,
	pgsql-hackers@postgresql.org, Guillaume ERGAND <ger@4js.com>
Subject: Re: PostgreSQL 8.3, libpq and WHERE CURRENT OF
References: <4721BAFE.3080601@4js.com> <4721BF34.80901@enterprisedb.com>
	<4721DECF.80401@4js.com> <10801.1193404182@sss.pgh.pa.us>
	<4721F289.7080800@4js.com>
In-Reply-To: <4721F289.7080800@4js.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

Forget this one, just missing the WITH HOLD option...
Must teach myself a bit more before sending further mails.
Seb

Sebastien FLAESCH wrote:
> Ok...
> 
> Tested with 8.2.3:
> 
> Actually you can't DECLARE a cursor outside a transaction:
> 
> test1=> declare c1 cursor for select * from dbit2;
> ERROR:  DECLARE CURSOR may only be used in transaction blocks
> 
> That's the main reason why we don't use DECLARE CURSOR...
> 
> I understand we could use DECLARE CURSOR when a FOR UPDATE is
> detected, to allow UPDATE/DELETE WHERE CURRENT OF - these only
> make sense inside a transaction...
> 
> But for normal cursors, we need to support multiple active result
> sets that can last outside a transaction block.
> 
> Basically, we need all what you can do with ODBC cursors.
> 
> Anyway, thanks for your help.
> 
> Seb
> 
> Tom Lane wrote:
>> Sebastien FLAESCH <sf@4js.com> writes:
>>> Does a simple PQPrepare() with a SELECT statement not create a cursor on
>>> the server side?
>>
>> No.  A prepared statement is just a query plan, not a query-in-progress.
>>
>> The Bind/Execute messages sent by PQexecPrepared create something akin
>> to a cursor, but libpq doesn't expose any API for fetching one row at a
>> time in that context, so there's no way to use the "current row" anyway.
>>
>>             regards, tom lane
>>
> 
>