FreeTDS Development Group

["James K. Lowden" <jklowden AT speakeasy.org>]

Michael Peppler wrote:

>  >From what I'm seeing, MS is, by default under TDS 7.0, actually sending
>  > the entire text clob all in one go.  So technically they are sticking to
>  > the protocol. It just makes the maxlength value useless for preallocating
>  > memory!
>
> What?!?!
>
> Don't they honour the default TEXTSIZE value?
>
> (oh, and of course they don't allow setting CS_OPT_foo via
> ct_options() either, so you have to execute it as a language statement
> for that connection)

Well... MS doesn't offer a ct-lib client, so we can't really say what they 
do. :-{  Would
better ct_option support in FreeTDS make DBD::Sybase better?

>  > If freetds were to allow a "set textsize" to be executed automatically on
>  > connect, ct_describe would return a sane value and everyone should be
>  > happy.

If I read Brian's message right, ct_describe doesn't return a value 
representative of
TEXTSIZE until it's been explicitly set, which is (as Mr.Friesen observes) 
less than
helpful.  A pain in the tookus, my grandfather would have said.

The documentation http://larr.unm.edu/~owen/SQLBOL70/html/globals_26.htm  
says:

"The default size is 4096 bytes (4 KB)."

Houston, we have a bug.

May I offer a suggestion?

If you're going to send "set textsize" on connect, maybe the default value 
(in the absence of
a config file value) should be 32 KB cf. Sybase or 4 KB cf. Microsoft?  
Principle of least
astonishment and all that?  I think that would cut down on the number of 
questions.  Better
truncated data (which the calling application can should test for in any 
case) than a broken
query.

If someone objects that they don't want to pay the overhead of sending a 
query on every
connection for a feature they don't use, which might be reasonable in some 
web environments,
the config file could have the option to skip it:

That would leave 3 behaviors:

1.    No config file entry.  Send "set textsize = 32 * 1024" or "set textsize 
= @@textsize".
2.    Config file entry reads "textsize=X" where X is between 0 and a maximum 
length of 2^31
- 1.
Result:  Send "set textsize= X".
3.    Config file entry reads "textsize=default" (literally).  Result: Do 
nothing.

How's that sound?

There's a fly in the ointment, too: unicode.  "Textsize" is measured in 
bytes, not
characters.  Just when you thought you knew what text is, the world goes 
multilingual on you.

"In our country," said Alice, still panting a little, "you'd generally get to 
somewhere else
-- if you ran very fast for a long time as we've been doing."

"A slow sort of country!" said the Queen.  "Now, *here*, you see, it takes 
all the running
you can do, to keep in the same place."

OK.  I'll stop kibitzing now and return to the docs.

--jkl