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Let's drop V2 protocol

From: Marko Kreen <markokr(at)gmail(dot)com>
To: Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)oss(dot)ntt(dot)co(dot)jp>
Cc: greg(at)2ndquadrant(dot)com, pgsql-hackers(at)postgresql(dot)org, mmoncure(at)gmail(dot)com,shigeru(dot)hanada(at)gmail(dot)com
Subject: Let's drop V2 protocol
Date: 2012-02-24 13:52:10
Message-ID: 20120224135210.GA11282@gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Fri, Feb 24, 2012 at 02:11:45PM +0200, Marko Kreen wrote:
> On Fri, Feb 24, 2012 at 07:53:14PM +0900, Kyotaro HORIGUCHI wrote:
> > - I have no idea how to do test for protocol 2...
> 
> I have a urge to test with "rm fe-protocol2.c"...

Now I tested with 7.3.21 and the non-error case works fine.  Error state
does not - and not because patch is buggy, but because it has never
worked - V2 protocol has no working concept of skipping packets because
pending error state.

On OOM, V2 code does:

   conn->inStart = conn->inEnd;

and hopes for the best, but it does not work, because on short results
it moves past ReadyForQuery, on long results it moves into middle of
some packet.

With user-specified row processor, we need to have a working
error state handling.  With some surgery, it's possible to
introduce something like

   if (conn->result->resultStatus != PGRES_TUPLES_OK)

into various places in the code, to ignore but still
parse the packets.  But it will be rather non-trivial patch.

So could we like, uh, not do it and simply drop the V2 code?


Ofcourse, the row-processor patch does not make the situation worse,
so we could just say "don't use custom row processor with V2 servers",
but it still raises the question: "Does anyone have pre-7.4
servers around and if yes, then why does he need to use 9.2 libpq
to access those?"

-- 
marko


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