Multithreaded Search using c#

Tuesday, August 17, 2010 by Nate Bross

Someone asked on Stack Overflow:

I want to seach more than 15000 values in a select statement as shown below:

select * from tableA where id in (1,2,3......16000)

Can I use threads, say around 3, and partion 15000 values in diffrent select statement.

1. select * from tableA where id in (1,2,3......5000)
2. select * from tableA where id in (5001....10000)
3. select * from tableA where id in (10001....15000)

and run these 3 select statment in parallel.

I posted the following answer, which was chosen as the accepted answer and received 2 upvotes:

Yes, but the real question is why?

Something like this might get you started:

var itms = new List<YourDataClass>();

var thr1 = new Thread(new ThreadStart(delegate()
{
    // select code
    // populate itms
}));
var thr2 = new Thread(new ThreadStart(delegate()
{
    // select code
    // populate itms
}));
var thr3 = new Thread(new ThreadStart(delegate()
{
    // select code
    // populate itms
}));

thr1.Start();
thr2.Start();
thr3.Start();

However, that said, if your IDs are integers and (based on your sample) the range of IN values are sequential, you might want to switch to a where id > 1 and id < 16000 style. This may yeild better performance.

Originally posted on Stack Overflow — 2 upvotes (accepted answer). Licensed under CC BY-SA.