I would argue that in certain types of applications knowing that you
can achive the "C" with code logic, dirty reads can lead to a
significant performance boost...

Yoni.


--- In firebird-support@yahoogroups.com, Helen Borrie <helebor@...>
wrote:

>
> At 10:32 PM 14/04/2008, you wrote:
>
> >I need a clarification... NOLOCK enables the SELECT statments to

read

> >uncommitted data. That is: if another process runs an UPDATE

statment

> >the SELECT statment will not get locked.
> >
> >This is what SQL Server calls a hint which override the default
> >behaviour (read committed and get locked)
> >
> >Does firebird support this? If not can I make sure that the

default

> >behaviour would be "read uncommited"?
>
> No, Firebird does not support Dirty Read under any circumstances,

never-ever-ever. It's a plus, not a "missing feature"! The "C" in
ACID stands for "consistency", which is not achievable in a database
engine that allows (or cannot avoid) Dirty Reads.

>
> A transaction can read its own uncommitted work but never the

uncommitted work of others. A Read Committed transaction can read
the work committed by others immediately and will respond to those
changes if required, according to its own transaction parameters.

>
> It seems you still need to tell us what you want to achieve so that

we can advise you on the transaction parameters you need...

>
> ./heLen
>