Re: Extended Query, flush or sync ? - Mailing list pgsql-general

From Raimon Fernandez
Subject Re: Extended Query, flush or sync ?
Date
Msg-id A321ADD5-6C0F-46F5-87EA-EAEBA6420442@montx.com
Whole thread Raw
In response to Implementing Frontend/Backend Protocol TCP/IP  (Raimon Fernandez <coder@montx.com>)
Responses Re: Extended Query, flush or sync ?  (John DeSoi <desoi@pgedit.com>)
List pgsql-general
Hello,

On 19/12/2009, at 4:31, John DeSoi wrote:

>
> On Dec 18, 2009, at 4:44 PM, Raimon Fernandez wrote:
>
>> It's not clear for me if I have to issue a flush or sync after each process of an extended query.
>>
>> It's almost working for me only when I send a sync, but not when I send a flush. With the flush, the connection
seemsfreezed, or at least, I don't get any data from postgre. 
>>
>>
>> - Send the parse command
>> - sync
>> - Receive the ParseComplete
>> -sync
>> - Send the Bind
>> - sync
>> - Receive the BincComplete
>> - send the Execute
>> - receive an error => "portal xxxxxxx does not exist"
>
>
> I send:
>
> parse
> bind
> describe
> execute
> sync
>
> and then loop on the connection stream to receive the responses.

And do you get the parseComplete after sending the parse or after sending the sync ?

I'm not getting parseComplete, bindComplete if I don't send a sync after each command.

If I follow your advice, after the sync, I get the parseComplete, bincComplete, and portalSuspended (beacuse I've reach
themax rows) 

Don't know if your correct approach is the correct, but why send a Bind if we don't know if the parse has been
successfullycreated ...  

From the docs:

 "A Flush must be sent after any extended-query command except Sync, if the frontend wishes to examine the results of
thatcommand before issuing more commands. 
Without Flush, messages returned by the backend will be combined into the minimum possible number of packets to
minimizenetwork overhead." 

Ok, I see that both approachs should work, but for me, sending a flush after each extended query command like parse,
bind,... doesn't do nothing ... 


And also from the docs:

"If Execute terminates before completing the execution of a portal (due to reaching a nonzero result- row count), it
willsend a PortalSuspended message; t 
he appearance of this message tells the frontend that another Execute should be issued against the same portal to
completethe operation. " 

If I execute with a row limit of 1000, and I know there are more than 1000 rows, I get the portalSuspended as
described.

But, If a issue a new Execute, postgresql says that myPortal doesn't exist anymore.

How I can get those 1000 rows ?


thanks !

regards,


raimon




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