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  • From: "Lowden, James K" <LowdenJK AT bernstein.com>
  • To: <ml AT freetds.org>
  • Cc:
  • Subject: [freetds] ct-options
  • Date: Tue, 12 Apr 2005 12:29:54 -0400

> From: Thompson, Bill D (London)
> Sent: Tuesday, April 12, 2005 8:36 AM
>
> I'll have a go at ct_options().
> I had started to look at it anyway.

Sounds good, Bill.

> I reckon that the ctlibrary ct_options(CS_OPT_CHAINXACTS),
> and its partner "SET" option "SET CHAINED..",
> are the same as SQL server's "SET IMPLICIT_TRANSACTIONS ON"
> command. They seem to be the same thing as far as I can tell.

I think so; that's what I had in mind. I haven't traced a ct-lib
conversation with tcpdump.

We're going to need a whole new structure, to support the GET option.
The information is not always (conveniently) available from the server,
and the Open Client Client-Library/C Reference Manual indicates the
settings are maintained by the library:

"
A Client-Library application sets and clears Adaptive Server
query-processing
options in one of two ways:

* By using a Transact-SQL language command (set)
* By calling ct_options

An application may use only one of these methods; otherwise, Client-
Library/server communications may become confused.

The ct_options method is recommended because it allows an application to
check the status of an option, which is not allowed by the Transact-SQL
set
command.
"

I don't see how "communications may become confused"; I don't see any
reason for ct-lib to refer to settings that were transmitted to the
server. But I can easily see that an application (or application
programmer) might become confused, if it sent a language command and
then attempted to ascertain the new status with ct_options().

It looks to me like Sybase wanted to provide the appearance of being
able to interrogate the server's status, but supplied responses from a
local one-way cache. Maintaining 1 datum in 2 places is always a can of
worms....

--jkl


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