Subject: Re: [HACKERS] More thoughts about FE/BE protocol
From: Bruce Badger <bruce_badger@badgerse.com>
To: pgsql-interfaces@postgresql.org
In-Reply-To: <7705.1050017370@sss.pgh.pa.us>
References: <10478.1049927451@sss.pgh.pa.us> <3E95A3CD.9080500@xythos.com>
	<5564.1049998513@sss.pgh.pa.us> <1050012887.1063.12.camel@alice>
	<7705.1050017370@sss.pgh.pa.us>
Content-Type: text/plain
Content-Transfer-Encoding: 7bit
Date: 11 Apr 2003 12:21:41 +1000
Message-Id: <1050027702.3103.59.camel@alice>
Mime-Version: 1.0

On Fri, 2003-04-11 at 09:29, Tom Lane wrote:
> Bruce Badger <bruce_badger@badgerse.com> writes:
> > Is SYNC going to be a new kind of message?  Is the SYNC response yet
> > another?
> 
> Yes; no.  SYNC response already exists: it's ReadyForQuery (Z).
> 
> > Either way, could this be used as a keep-alive for long-lived
> > connections?  (some users of the current Smalltalk drivers report that
> > long lived connections over the Internet sometimes just die)
> 
> If you're worried about that, Q with an empty query already suffices,
> though SYNC will work too.
> 
> I'd be inclined to think that such breakage isn't our problem though;
> anyone suffering from it needs to fix their firewall timeouts ...

Oh, I agree.  But not everyone has control over the firewalls they have
to work through, and not all admins have enough (any?) motivation to
help.  A keep-alive could be a useful option in an unhelpful world.

> > Also, with the new protocol, will the number of affected rows be 
> > returned in a way that does not require parsing to fish it out?
> 
> I'm not planning to change the contents of messages more than I have to.
> What's so hard about parsing "UPDATE nnn" ?

Nothing, of course.  However the fewer easy things we *have* to do, the
more other things we have time for.  Also, some things that could return
a row count don't, e.g. SELECT.

And to turn the question around: What's so hard about adding in an Int32
in the 'C' (CompletedResponse) message which gives a row count?  Then,
if people want to display "UPDATE nnn", they can concatenate the string
'UPDATE' with the number - even easier than parsing - at least in
Smalltalk :-)

... then, having a code to indicate the kind of thing completed (like
the code used in the 'R' (AuthenticationXxx) messages means you could
lose the string in the message altogether.