[freetds] idea: eliminate port/instance

James K. Lowden jklowden at freetds.org
Sat Apr 4 15:29:25 EDT 2009

I propose to eliminate "port" and "instance" from freetds.conf.  I'd like
feedback on the idea.  

In freetds.conf, one can specify:


Port and instance are mutually exclusive.  People get confused; they
specify both, and then don't know (because we don't say) that port
overrides instance.  You could think of that as a failure ... of
documentation or of design.  

My first thought was to eliminate "instance", and use port as follows:

1.  If port is numeric, it's a port.
2.  If port is non-numeric, try looking up the port with getservbyname(3).

3.  If getservbyname(3) fails, look up the port using the UDP instance

We could instead print loudly to stderr when both port and instance are
found in the same section. But that won't help when Apache is involved
and/or standard error is closed. 

But overloading "port" to sometimes mean an instance name could also sow

Simplest is to eliminate port *and* instance, and denote it this way:

	host = servername:port
	host = servername:instance

and apply the above three rules to whatever is right of the colon.  

That mimics URL notation and config.c::parse_server_name_for_port().  

I would stop supporting port & instance immediately.   The release notes
would alert users to the change.  I don't want to support both because the
whole problem is confusion stemming from needless complexity.  

At the same time, I would change the freetds.conf parser to emit messages
on standard error when it finds problems in the file.  (Currently
misconfigurations and unknown options are silently ignored.)  That will
help people using, say, tsql to know their setup has a problem.  

Thoughts?  Patches?  Anyone out there with a freetds.conf that would take
more than a few minutes to update?  


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