At 14:01 -0600 3/10/03, Pete Harlan wrote:
On Mon, Mar 10, 2003 at 11:32:06AM -0600, Paul DuBois wrote:
Whether it's a feature or not, it's not always so easy to figure out
what to do. If you specify -h localhost, it can be argued that you
really want the socket even if you specify the port. It can be
argued conversely that if you specify the port, you should use TCP/IP
even if you specify -h localhost.
That is, if the user specifies both, it's ambiguous what the user really
wants.
But "localhost" is a DNS name that only happens to resolve to
127.0.0.1. MySQL breaks this DNS abstraction by treating "localhost"
as a keyword, different from 127.0.0.1, which goes against the
principle of least surprise. (It confused me, anyway.)
I think it would have been less confusing to treat "localhost" the
same as its resolved IP address, and decide whether to use a local
socket vs. a port number on the basis of a different argument (-l for
local, perhaps, which would be the default when connecting to
127.0.0.1 (or localhost, or any other name that resolved to this IP)).
In 4.1, there will be a --protocol option that allows the connection
type to be specified. This will have the effect of allowing the user
to specify intent unambiguously.
Wild speculation: The current design was chosen back when MySQL didn't
have different sections in /etc/my.cnf, so the port specification for
the server was also used for the client. In that case the client
usually read a port specification (in /etc/my.cnf), but in the common
case the client wouldn't obey it, which typically did the right
thing. (Now that there are separate [client] and [server] sections in
my.cnf things are less jumbled.)
That is indeed speculation, and it's incorrect. Option files were
introduced around 3.22.10, and they've always had sections.
The client could be made to obey a command-line argument, while still
silently ignoring the my.cnf argument. (That's what my patch did.)
It's not just the mysql client, it's the client library, which is what
bit us. You specify a port in the DBI->connect() routine as something
like ';host=localhost;port=2000' and it's silently ignored there too.
Well, sure. Options just map onto arguments to the mysql_real_connect()
C library call, and the ambiguity of intent carries all the way down
to that level.
I'm very glad that ssh no longer (as of three years ago!) forwards
externally-connected-to ports by default.
--Pete
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