On Dec 9, 1:03 pm, Jason Meckley <[email protected]> wrote:
> ""Also does NH support MARS (multiple active record set) in SQL server
> where I potentially can stream ALL the data"
> I thought this is what NH is using under the hood to support
> MultiQuery/Criteria and Future/FutureValue
>
>  I didn't know that - I'd always assumed it was more like a batch SQL
> with multiple record sets:
>
>  select x from a;
>  select y from b;"
>
> Yeah, I thought they are one in the same.

I think the difference is in MARS (when enabled) on same connection
you can do 2 concurrent commands:

command 1 - select x from a
command 2 - select y from b

Then iterate over the records from each in parallel.

http://www.sqlteam.com/article/multiple-active-result-sets-mars

This is slightly different from 1 command submitting 2 SQL in a batch.

> On Dec 9, 9:46 am, ajaishankar <[email protected]> wrote:
>
> > On Dec 9, 8:25 am, Jason Meckley <[email protected]> wrote:
>
> > > You may be able to do some form of ETL with NH and IStatelessSession.
> > > But again, is NH the right tool?
>
> > I already got everything going in a nice set based SQL batch (ETL) but
> > as new data points come in I'm having to replicate the logic at both
> > places :-(
>
> > Once in detached criteria & once in SQL which I wanted to avoid with
> > this exercise.
>
> > Am not convinces yet if it can all be done in NH since the metrics are
> > all aggregations.
>
> > > "Also does NH support MARS (multiple active record set) in SQL server
> > > where I potentially can stream ALL the data"
> > > I thought this is what NH is using under the hood to support
> > > MultiQuery/Criteria and Future/FutureValue
>
> > I didn't know that - I'd always assumed it was more like a batch SQL
> > with multiple record sets:
>
> > select x from a;
> > select y from b;
>
> > Which would then be lazily listed - though to the client it looks like
> > an enumeration...
>
> > > another approach is to process customer individually or in small
> > > batches each with a unique session.
>
> > Thanks Jason - I'll try this too but am liking a set based approach
> > most...
>
> > > On Dec 9, 9:01 am, ajaishankar <[email protected]> wrote:
>
> > > > I am in a situation where I need to retrieve a list of customers (>
> > > > 200K) and various metrics (over 15) for each customer.
>
> > > > Each one of the metrics collection code (such as #site_logins,
> > > > #csrcalls etc) are already neatly written in criteria queries - but on
> > > > a individual customer basis.
>
> > > > I was able to project each of these existing criteria into a group by
> > > > Customer.Id.
>
> > > > So now I have potentially a stream of data each detached criteria
> > > > generates:
>
> > > > Customers, CustomerLogin { CustomerId, NumLogin } , CSRCall
> > > > { CustomerId, NumCalls } and so on...
>
> > > > I want to enumerate each result for some calculation and do not want
> > > > to load everything to memory since it is a large data set
>
> > > > And doing the final (left) join in detached criteria I think is quite
> > > > complex...
>
> > > > I am at a point where I'm pondering the following:
>
> > > > 1. Is it possible to stick everything in a  multi-criteria and do the
> > > > final join there itself and get just the last record set?
>
> > > > 2. A criteria transformer into a query would be helpful so that I can
> > > > iterate enumerate the result
>
> > > > 3. Also does NH support MARS (multiple active record set) in SQL
> > > > server where I potentially can stream ALL the data...
>
> > > > Ajai
>
> > > > On Dec 9, 5:33 am, Diego Mijelshon <[email protected]> wrote:
>
> > > > > No, it's not possible. What do you need it for?
>
> > > > >    Diego
>
> > > > > On Wed, Dec 9, 2009 at 00:26, ajaishankar <[email protected]> 
> > > > > wrote:
> > > > > > Hi
>
> > > > > > Is it possible to do an Enumerate on a criteria than a List?
>
> > > > > > I see IQuery having an Enumerate method...
>
> > > > > > I'm trying to loop through the results similar to a data reader...
>
> > > > > > Thanks
>
> > > > > > Ajai
>
> > > > > > --
>
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