[geeks] SQL Performance

[Shannon Hendrix]

On Jul 23, 2008, at 12:54 , Joshua Boyd wrote:

> The reason for discussing DB usage on VxWorks or QNX was because of
> there not being a DB2, Oracle, or MS SQL client for those OSs, and the
> evils of an undocumented protocol for databases.  Are you saying that
> you have used Oracle, MS SQL, or DB2 from VxWorks?  Does that mean  
> that
> DB2 Everyplace works as a portable client library, in addition to  
> being
> an embedded database?  Even if it does, doesn't that leave you screwed
> if you want something like FreeRTOS or eCos instead to save on the  
> $10ks
> upfront, plus per unit licensing?

I was only commenting on the idea that you cannot do unpredictable  
things like remote database access in an embedded/realtime system.   
You just have to manage it properly and understand the limits you have  
to work within.

The undocumented interface issue is pervasive across all systems  
because of the poor support most vendors have for anything but a  
limited set of mainstream systems.  It just plain sucks all around.

Sometimes it is easier to just write your own database transfer  
protocol and use that between client and server, and then just make a  
little driver/buffer/cache whatever to feed the real backend  
database.   Helps with predictability and speed too.

Personally, I often found this faster and more predictable than trying  
to store the database on the VxWorks system, which presents its own  
set of problems.

In one case we threw hardware at the problem: the database server and  
the VxWorks machine both ran ScramNet to share data.  Works great if  
you can afford it.

That's one thing I miss about embedded development: the requirements  
often are such that you have no time for the kinds of bullshit you  
have to put up with in other development.

It either works or it doesn't.

No one ever bitched at me for what font I used when I was doing  
embedded work...




-- 
"Where some they sell their dreams for small desires."