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From: Omatase on 30 Sep 2009 23:30
I have a data in a table that I need to read once and only once. I
will have multiple instances of my application accessing this database
potentially at the same time (because my application is WCF service
hosted by IIS) but no two instances of this application should access
the same rows of data even on reads.

If I were in TSQL I could just do an XLOCK, ROWLOCK to lock the row on
a SELECT but I can't find any way to lock on a SELECT in linqtosql. I
know I can use TransactionScope to provide an isolation level but none
of the isolation levels will take an exclusive lock on a select
statement. While SERIALIZABLE seems to provide this functionality from
the description on Microsoft's site, in practice (I tested it in
Management Studio) it does not.

My questions are is there a way to take an exclusive lock on a SELECT
in pure LINQ or is there a way I can manage my concurrency directly in
the C# code? I haven't done anything with C# object transactioning and
I don't know if it can satisfy my requirement since I don't know how I
can share data across different instances of my WCF service and am not
really even sure a singleton or static class would accommodate me in
this situation.

Thanks for any help
From: "Mr. Arnold" MR. on 1 Oct 2009 00:23

"Omatase" <omatase(a)gmail.com> wrote in message
news:1be096bd-9550-4a69-996d-bdc7f0dd5ad2(a)z3g2000prd.googlegroups.com...
>I have a data in a table that I need to read once and only once. I
> will have multiple instances of my application accessing this database
> potentially at the same time (because my application is WCF service
> hosted by IIS) but no two instances of this application should access
> the same rows of data even on reads.
>
> If I were in TSQL I could just do an XLOCK, ROWLOCK to lock the row on
> a SELECT but I can't find any way to lock on a SELECT in linqtosql. I
> know I can use TransactionScope to provide an isolation level but none
> of the isolation levels will take an exclusive lock on a select
> statement. While SERIALIZABLE seems to provide this functionality from
> the description on Microsoft's site, in practice (I tested it in
> Management Studio) it does not.
>
> My questions are is there a way to take an exclusive lock on a SELECT
> in pure LINQ or is there a way I can manage my concurrency directly in
> the C# code? I haven't done anything with C# object transactioning and
> I don't know if it can satisfy my requirement since I don't know how I
> can share data across different instances of my WCF service and am not
> really even sure a singleton or static class would accommodate me in
> this situation.
>

You know the whole world doesn't center around Linq-2-SQL or even ADO.NET
Entity Framework.

There is nothing wrong in using ADO.NET SQL Command Objects with a Stored
Procedure with (T-SQL) along with using Linq-2-SQL or ADO.NET Entity
Framework within the same solution or C# application.

I don't see why you couldn't also cache the data in memory on IIS so that
subsequent access of the data is from cached data by the WCF Web Service. If
the cached data is not there, then you go read it from the database and
cache it.

I don't know SQL Command Object using an sproc, a datareader is used to read
the resultset, List<t> used to hold DTO(s) Data Transfer Object with
accessor properties that represents the fields of the table row, and put
into cache.



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From: Omatase on 1 Oct 2009 10:20

> You know the whole world doesn't center around Linq-2-SQL or even ADO.NET
> Entity Framework.

What? Of course it does! It has been scientifically proven that if MS
had not created Linq 2 Sql when it did we would not now have a
replacement for the previous "sun". Whew, that was a close one!
From: Mr. Arnold on 1 Oct 2009 12:12
Omatase wrote:
>> You know the whole world doesn't center around Linq-2-SQL or even ADO.NET
>> Entity Framework.
>
> What? Of course it does! It has been scientifically proven that if MS
> had not created Linq 2 Sql when it did we would not now have a
> replacement for the previous "sun". Whew, that was a close one!


I'll assume you have heard of nHibernate that was on the scene and used
by Java and .NET solutions long before Link-2-SQL or ADO.NET Entity
Framework came to be.

And besides, you're banking on the wrong technology Linq-2-SQL which is
to light in it's over all power and limitations as opposed to ADO.NET
Entity Framework.

http://www.develop.com/entityframework4
http://blogs.msdn.com/adonet/archive/2009/05/11/update-on-the-entity-framework-in-net-4-and-visual-studio-2010.aspx

Entity SQL like (T-SQL) it may not have row locking at this time, but
you can assume it's going to happen.

http://msdn.microsoft.com/en-us/library/bb387145.aspx

You do know that an ADO.Entity Framework Entity is an implicit WCF
serialized data contract.
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