Re: Loading the PL/pgSQL debugger (and other plugins)

> I'm unqualified to comment on the server side design, but I was 
> wondering if there was consensus on how the client interface to the 
> debugger would work. From previous threads I saw DBGP mentioned 
> (http://xdebug.org/docs-dbgp.php), but I don't recall seeing any final 
> commitment to it.
The patch that I'll be submitting for 8.2 will implement a way to 
instrument PL/pgSQL (and that idea can be extended to other PL 
languages).  'Instrumentation' can mean different things - it may be a 
debugger, a profiler, a coverage analyzer, a tracer, ... 

EnterpriseDB has developed a few plugins that we'll be contributing soon 
(a debugger, a profiler, and a tracer).  The debugger is by far the 
largest plugin that we've developed and we implemented it before we had 
the idea to use a modular architecture (we're still in the process of 
converting the debugger to modular form, at the moment it's pretty 
heavily integrated into the PL/pgSQL interpreter).  As soon as we get a 
patch in for the plugin architecture, we'll open-source at least one or 
two of the plugins so others can use them and/or write more (the 
debugger will take a little longer). 

That means that we (i.e. the community) haven't made a firm commitment 
to the debugger client protocol.  I can tell you a little about the 
protocol that we are currently using, but it may change by the time 
we're ready to open-source the debugger.  I gave a presentation at the 
anniversary summit that described the overall architecture and also 
showed the client/server protocol - the slides and audio should be 
available at the conference web site "real soon now". 

The most important part, from your perspective (assuming that you might 
want to add a debugger to pgEdit), is the method that a debugger client 
application uses to interact with the debugger server.  That's done 
through a collection of server-side functions that you can call from any 
libpq application.  For example, to set a breakpoint, you would:
   SELECT * FROM pldbg_set_breakpoint( sessionHandle, functionOID, 
lineNumber, processID );

to step/over:
   SELECT * FROM pldbg_step_over( sessionHandle );

to step/into:
   SELECT * FROM pldbg_step_into( sessionHandle );

to get a copy of all local variables:
   SELECT * FROM pldbg_get_variables( sessionHandle, stackFrame );

and so on.  There are a few functions that you can call to attach your 
debugger client to a target server and to set global breakpoints.

I'll be posting more information as we get closer to releasing this stuff. 
            -- Korry