FreeTDS Development Group

[ZIGLIO Frediano <Frediano.Ziglio AT vodafoneomnitel.it>]

> 
> Here is Sybase ASA 5.5 using OSG (OpenServer Gateway).  The 
> spid entry is 
> '0'.  IIRC, sybase ASE does the exact same thing, so this is 
> an MS only 
> thing.  
> 
> Received header @ 2003-02-21 18:49:35.436953
> 0000  0f 01 00 2d 00 00 01 00                            |...-....|
> 
> Now, when doing a 
> 
> exec server2.db1..myproc
> 
> then your local server connects to server2 and called the 
> stored proc in 
> your place.  In the instance that two people make a stored 
> procedure call 
> like this, it multiplexes the commands over a single tcp 
> session using (I 
> believe) the two byte spid in the header to keep things 
> straight.  So, 
> it's there in sybase, just turned off most of the time we are looking 
> (client to server).
> 
> Anyway, it doesn't buy us much because we still have to issue select 
> @@spid in most instances.
> 
> Speaking of which though, this week I was looking at the 
> Sybase ASE 12.5 
> migration guide.  One of the features there was they upped 
> the max number 
> of users from 2^16 to something bigger.  So, it is likely 
> that by setting 
> the right capabilities under the TDS 5.0 login packet that 
> select @@spid 
> may have broke anyway.  This is all unconfirmed conjecture of course.
> 

I know, this is only a mssql feature, but can save a bit of exchange during
login.
Also I found the thing weird... if mssql can handle only a connection for
every tcp connection why storing @@spid for every packet? Perhaps other bit
mean login, so you can enable another "virtual" connecttion on same tcp
connection, like Sybase ?

freddy77

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