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  • From: Matthew Gates <MGates AT redplc.com>
  • To: FreeTDS Development Group <freetds AT lists.ibiblio.org>
  • Subject: [freetds] Transaction getting stuck in SQLBindCol
  • Date: Fri, 18 Mar 2011 17:37:12 +0000

My program is sometimes getting stuck in a call to SQLBindCol. It's rare -
of the order of one call in two million - and variable. I can't run with any
sort of verbose debugging, so I plan to instrument the SQLBindCol function to
find where the problem is.

SQLBindCol is called twice - once for a SQL_C_SLONG and once for a SQL_C_CHAR
string (which can be quite long - sometimes more than 1000 characters in
length). I'm working to determine which call it is and the exact length of
the requested string when the problem occurs, but it's very slow going since
I have to instrument up the binary and then wait a long time for the problem
to occur.

Does anyone have any hints of what to look for? I'm afraid I don't really
understand what is going on at this low level. When SQLBindCol is called, is
any connection to the database required which might be blocking due to a
sporadic network issue? Where else might a problem lie?

The result of this stuckness is that the connection gets killed from the
database end. At this point the SQLBindCol call returns (without error in
fact), and the process continues. I don't know if that lack of detection of
a problem is relevant or not.


Regards,
Matthew



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