Well, using NHProf (why didn't I think of that before?)

So to answer my own question "no there is no reace condition"


Details:

1)
begin transaction with isolation level: Unspecified

2)
Reading high value:
select next_hi
from   hibernate_unique_key with (updlock ,rowlock)

3)
Updating high value:
update hibernate_unique_key
set    next_hi = 1590 /* @p0 */
where  next_hi = 1589 /* @p1 */

4)
Reading high value:
select next_hi
from   hibernate_unique_key with (updlock ,rowlock)

5)
Updating high value:
update hibernate_unique_key
set    next_hi = 1591 /* @p0 */
where  next_hi = 1590 /* @p1 */

6)
Inserting my order

7)
Insert an address

8)
commit transaction



The reason I am seeing two updates of the key table is that each
entity gets its own high value.

Thomas

On 10 Sep., 14:05, Fabio Maulo <[email protected]> wrote:
> since the source of "high" is concentrated in one place.... ;)
>
>
>
>
>
> On Fri, Sep 10, 2010 at 8:58 AM, Thomas Koch <[email protected]> wrote:
> > Hi - I use the hi-lo generator for my domain and have a question
> > regarding its use in multiple processes.
>
> > I have a WCF project that is the primary power behind generating
> > entities and saving them to the database with NHibernate and HI-LO. I
> > also have an administrative application that sometimes generate
> > entities for the domain.
>
> > Since these two applications live en separate processes, is there a
> > risk here of them creating overlapping id's ?
>
> > As far as I have understood, each session factory will update the
> > "hibernate_unique_key" table and generate ids based on the "high"
> > value returned.
>
> > Can the reading and updating of this "next high value" be considered
> > an atomtic operation even though its done in separate processes?
>
> > Regards
> > Thomas
>
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> Fabio Maulo- Skjul tekst i anførselstegn -
>
> - Vis tekst i anførselstegn -

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