[freetds] How to set tsql's client character set
Lowden, James K
james.k.lowden at alliancebernstein.com
Fri Aug 11 13:13:47 EDT 2006
> From: KJ
> Sent: Friday, August 11, 2006 10:12 AM
> > Nice work!
> > The goal is to make it unnecessary to declare the client charset
> > in freetds.conf for a correctly configured machine. That is, we
> > want to rely on the locale settings unless overridden by
> > freetds.conf.
> > Steve Langasek submitted a patch for 0.64 to do that but it was
> > late in the release cycle. I eventually decided to defer it
> > because there are a lot of permuations and I wanted to look at
> > it more closely. :-(
> I just went through the ML and found that stuff quiet confusing.
> I don't understand what's the difference between server/wire
> character set and client character set. Sybase tools (isql, bcp)
> offer an additional option -J for specifying the client's character
> set. If that option is missing the platform's default is being
> used, if followed by a charset then that one is used, if -J is
> specified without parameter, then the server's characater set is
> used, whatever it might be (in the latter case no charset is being
> sent in the login record). Hence the client does not have to know
> server's charset. The character set conversion is done on the
> server. If both character sets are equal no conversion is done
> otherwise the conversion rules applies (with or without conversion
> My suggestion is to use the approach above, without usage of any
> *.conf file (concerning char sets!).
While I agree that implementing Sybase's charset control options would
be useful (particularly for bcp), I also think it's a distraction.
Fundamentally, we have to pass the correct client charset in the TDS 5.0
login record. We're really just talking about how the default is
determined. We want to use the following order:
1. programmatic setting (-J, DBSETLCHARSET)
IOW, if the application sets the charset, we ignore freetds.conf, else
we look in freetds.conf. If it's not set there, we rely on the locale.
That way, for a correctly configured machine -- i.e. one that can
display characters in the charset indicated by the locale -- everything
Just Works. For some applications, say a server that itself is ISO
8859-1 but generates HTML documents in UTF-8, the freetds.conf override
I don't want to waste your time. I suggest you either apply Steve's
patch to try to roll your own, such that the locale doesn't override
your freetds.conf setting. Then I think you'll be home free.
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