Message-Id: <200104162044.PAA00749@selkovjr.xnet.com>
To: Lonnie Cumberland <lonnie_cumberland@yahoo.com>
Cc: pgsql-interfaces@postgresql.org
From: selkovjr@mcs.anl.gov
Reply-to: selkovjr@mcs.anl.gov
Subject: Re: backend debug information 
In-reply-to: <20010416192226.52764.qmail@web12503.mail.yahoo.com> 
References: <20010416192226.52764.qmail@web12503.mail.yahoo.com>
Comments: In-reply-to Lonnie Cumberland <lonnie_cumberland@yahoo.com>
	message dated "Mon, 16 Apr 2001 12:22:26 -0700."
Date: Mon, 16 Apr 2001 15:44:32 -0500


Take it easy, Lonnie! I am still working on your earlier question :)

> I am getting this:

> trdata=# select desdecrypt('a','b');
> pqReadData() -- backend closed the channel unexpectedly.
>         This probably means the backend terminated abnormally
>         before or while processing the request.
> The connection to the server was lost. Attempting reset: Failed.
> !# \q  

You've probably got a segv. There's very little else that can happen
in your code. That in turn could be caused by writing at an overflown
pointer or by returning the wrong type. 

As far as debugging, short of being able to run a postgres under gdb
while connecting clients to it (I wish I knew whether that was at all
possible), your options are:

1. (preferred) -- fprintf(stderr, ,) from within your code; then watch
the logs or simply start your postmaster from a shell without
detaching it and see the output.

2. Make a wrapper that walks like a postgres and talks like a postgres
but does nothing except it calls your function and checks the return
value; then run that stuff in gdb.

As a general rule,

3. Slow down. Proceed in small increments. Start with a blank function
and make sure you can pass the desired arguments to it. Return
nothing. Check the values you pass with fprintf. Then add a return
statement and see if you can get away with it. Check it on the outside
with a SELECT. After that, keep adding the code in small logical
units. If it breaks, insert fprintf's to see where. Fprintfs are
almost as good as debugger breakpoints.

I'll be back with more stuff regarding the datatypes shortly.

--Gene