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Re: [INTERFACES] Frontend/Backend Protocol

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: jdale(at)fla(dot)fujitsu(dot)com
Cc: pgsql-hackers(at)postgreSQL(dot)org, pgsql-ports(at)postgreSQL(dot)org, pgsql-interfaces(at)postgreSQL(dot)org
Subject: Re: [INTERFACES] Frontend/Backend Protocol
Date: 1999-07-23 00:30:31
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackerspgsql-interfacespgsql-ports
Jonathan Dale <jdale(at)fla(dot)fujitsu(dot)com> writes:
> And I get back:
> "R" 00 00 00 00  which indicates a successful connection

Looks good so far (I suppose you are using 'trust' authentication mode).

> However, when my process has read this, the postmaster displays the
> following error:

> FATAL 1:  Socket command type   unknown

> and the connection is closed.

No, the postmaster didn't send that; the backend did.  Looks like you
sent one byte too many, probably a null byte, and the backend received
it as the first input data byte.  Since it's not a valid protocol
command character, the backend gives up and dies.

> I assumed that the
> postmaster would fork a new postgres process to handle my connection

... it did ...

> and I should be expecting some data on the socket to tell me that the
> postgres process is ready for an SQL query.

You should have gotten a ReadyForQuery message if you are talking to
a 6.4 or later backend, and if you used the right protocol version
number in the connect request.  I speculate that you have an old server,
or you asked for protocol version 1, or you miscounted bytes and missed
the appearance of the ReadyForQuery ('Z') message.

			regards, tom lane

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