Re: modifying the table function

Thanks for the documentation link. It helped me to understand how data are 
passed back to the client.

I figured out that data is sent back to the client using the 'printtup' 
function. It is called by ExecSelect, called by ExecutorRun, etc. What I 
understand now is that the data is sent to the client and stored there until 
the client receives a message from the server to display it. The server 
sends the display message from within 'ReadyForQuery' but I can't figure it 
out.

What I expect is that when I call 'exec_simple_query' several times, the 
server sends one row only for each call. But since they are separate calls, 
the client overwrites the previous results or saves the new row in a new 
place in memory such that it displays the last row only when the server 
invokes 'ReadyForQuery'.

I wonder if I am on the right track or not and how to know such kind of 
message sent from the server?

Regards
Islam Hegazy

----- Original Message ----- 
From: "Tom Lane" <tgl@sss.pgh.pa.us>
To: "Islam Hegazy" <islheg@gmail.com>
Cc: <pgsql-hackers@postgresql.org>
Sent: Tuesday, April 17, 2007 1:44 AM
Subject: Re: [HACKERS] modifying the table function


> "Islam Hegazy" <islheg@gmail.com> writes:
>> My question is how to inform the client that there is a tuple to display 
>> =
>> and return back to the backend to continue the query execution?
>
> I'd suggest you start by reading
> http://developer.postgresql.org/pgdocs/postgres/protocol.html
> and then develop a clear specification at that level of what you
> think should happen.  Perhaps after that exercise it will be clearer
> how to change the code.  "Think first, program later."
>
> regards, tom lane