Re: SQL/MED compatible connection manager

On Thu, Jan 01, 2009 at 11:10:38PM +0200, Martin Pihlak wrote:
> Peter Eisentraut wrote:
> > Well, what this function essentially does is a text transformation of the 
> > options, something like this:
> > 
> > peter=# SELECT array_to_string(fdwoptions || srvoptions || umoptions, ' ') 
> > FROM pg_foreign_data_wrapper fdw, pg_foreign_server srv, pg_user_mappings um 
> > WHERE fdw.oid = srv.srvfdw AND srv.oid = um.srvid;
> >                    array_to_string
> > -----------------------------------------------------
> >  host=localhost port=5432 user=peter password=seKret
> > (1 row)
> > 
> > (You can enhance this with quoting etc., but that's the essence.)
> 
> Essentially yes. Additional things include USAGE check on the server and user
> mapping lookup (use public if no explicit mapping is specified). Without those
> I'm not really sure this deserves a separate function at all. The main goal
> is to provide standard semantics for the connection lookup, so that dblink,
> plproxy, pl rpc etc. would not have to reinvent it.
> 
> > So, we could add a function whose job it is to convert all options to a 
> > PostgreSQL connection string.  I wouldn't worry about dealing with other 
> > wrappers specifically.  They could still use the function, but the result 
> > would not make much sense.
> > 
> This works for me. I'd implement this as a C function so it is
> directly callable from other C modules.
> 
> Another option is to implement it as a SRF, similar to what was
> initially in the dummy wrapper. Just return all of the options for
> fdw, server and user mapping.  This is probably worth doing if there
> are any users for this. So far I haven't noticed any enthusiasm, so
> it might be better to start with just the connection string.

The connection string could be pretty different if it's not a
PostgreSQL database, so +1 on the SRF option :)

Cheers,
David.
-- 
David Fetter <david@fetter.org> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
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