Re: Windows Ada database support.

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Mon, 29 Nov 2004 14:07:45 +0000 (UTC), Georg Bauhaus wrote:

> Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> wrote:
> 
>:  It is no different from, say, GTK, which
>: hides from you either Win32 or X11. You do not care about closing windows
>: handles when you are using GTK.
> 
> Depending on how my application must use windows, I might have to think
> about closing window handles.

... under X11.

>:>: It is all compiler vendor business. As an application
>:>: developer, I want to hear nothing about cursors.
>:> 
>:> Neither would I but I have to.
>: 
>: Yes, because bindings are thin.
> 
> No, I have to think about cursors because
> - they have a life time,
> - they are linked to a limited number of connections,
> - they are a limited resource themselves,
> - and they point to shared data, subject to updates.
> 
> This is interfacing to "world", not to some abstraction. The real
> problems have got little to do with the thickness of bindings, I think.
> In a multitasking, multiclient environment use of resources like cursors
> pointing to shared structured data means a lot in terms of resources as
> I'm sure you know. There is the additional burdon of managing a number
> of transaction logs, which is costly, and might incur locking.

Which only supports the point that cursor might be wrong abstraction.

>   See also Frank Piron's comment about implicit cursors in
> PL/SQL.
> 
>:>:> How much precision can you portably specify for floating point
>:>:> values in your DB independent package?
>:>: 
>:>: The required precision should specify the application.
>:> 
>:> Yes but this also influences what will be in this version of that
>:> DB.
>: 
>: So what? As long as my application uses Ada.Database, I do not care.
> 
> You should care. For instance, you might have large amounts of numeric data
> and your DB can store them as strings of decimal digits using thick
> Ada.Database facilities, or else you have to manually tweak and force things
> at low level and use tricks. Thick abstractions might take too much time.
> Thick abstractions leave some choices behind. This isn't always helpful.

Surely, but statistically irrelevant. Otherwise we would have no Ada and
still were programming in assembly. So there were no cursors, no data base
engines, no operating systems etc. Because one can always imagine a case,
where manual positioning of the hard drive heads could be essential for
performance.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de