Re: Pessimistic Locking

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> -Is there any possibility to prevent other clients to read the locked data
> which is being updated?

Yes, right before your insert/update/delete .. run a Select (HOLDLOCK)

> -Is it possible to tell another client that this row is locked and
> therfore cannot be updated instead of simply blocking the update
> operation?

Yes, run the other client in serializable isolation level - he will deadlock
and be made the deadlock victim.

> -How can I know that the row cannot be updated when I populate the form
> with the data read from the locked row.

Whoaa !! I don't understand this one .. "with the data read from the locked
row" .. if the row is locked, how did you read the data ;-)

- Sahil Malik [MVP]
ADO.NET 2.0 book -
http://codebetter.com/blogs/sahil.malik/archive/2005/05/13/63199.aspx
----------------------------------------------------------------------------

"Ferdinand Zaubzer" <ferdinand.zaubzer@xxxxxxxxxx> wrote in message
news:%23C6EWH2%23FHA.3136@xxxxxxxxxxxxxxxxxxxxxxx
>I would like to use pissimistic locking for changing data on a database.
>(Yes, I know what I'm doing, it will scale poorly!)
>
> I tried it using a transaction with Isolationlevel "serializable".
> I set the select, insert, update and delete command of the DataAdapter to
> use this transaction.
>
> If I open a Row for editing, any other client trying to change the same
> row is blocked. But it is still possible to read the row which is locked
> for editing.
>
> So I have the following questions:
>
> -Is there any possibility to prevent other clients to read the locked data
> which is being updated?
>
> if not:
>
> -Is it possible to tell another client that this row is locked and
> therfore cannot be updated instead of simply blocking the update
> operation?
>
> -How can I know that the row cannot be updated when I populate the form
> with the data read from the locked row.
>
> Cheers
> Ferdinand


.

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