问题
from f in CUSTOMERS
where depts.Contains(f.DEPT_ID)
select f.NAME
depts is a list (IEnumerable<int>) of department ids
This query works fine until you pass a large list (say around 3000 dept ids) .. then I get this error:
The incoming tabular data stream (TDS) remote procedure call (RPC) protocol stream is incorrect. Too many parameters were provided in this RPC request. The maximum is 2100.
I changed my query to:
var dept_ids = string.Join(" ", depts.ToStringArray());
from f in CUSTOMERS
where dept_ids.IndexOf(Convert.ToString(f.DEPT_id)) != -1
select f.NAME
using IndexOf() fixed the error but made the query slow. Is there any other way to solve this? thanks so much.
回答1:
My solution (Guides -> List of Guid):
List<tstTest> tsts = new List<tstTest>();
for(int i = 0; i < Math.Ceiling((double)Guides.Count / 2000); i++)
{
tsts.AddRange(dc.tstTests.Where(x => Guides.Skip(i * 2000).Take(2000).Contains(x.tstGuid)));
}
this.DataContext = tsts;
回答2:
Why not write the query in sql and attach your entity?
It's been awhile since I worked in Linq, but here goes:
IQuery q = Session.CreateQuery(@"
select *
from customerTable f
where f.DEPT_id in (" + string.Join(",", depts.ToStringArray()) + ")");
q.AttachEntity(CUSTOMER);
Of course, you will need to protect against injection, but that shouldn't be too hard.
回答3:
You will want to check out the LINQKit project since within there somewhere is a technique for batching up such statements to solve this issue. I believe the idea is to use the PredicateBuilder to break the local collection into smaller chuncks but I haven't reviewed the solution in detail because I've instead been looking for a more natural way to handle this.
Unfortunately it appears from Microsoft's response to my suggestion to fix this behavior that there are no plans set to have this addressed for .NET Framework 4.0 or even subsequent service packs.
https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=475984
UPDATE:
I've opened up some discussion regarding whether this was going to be fixed for LINQ to SQL or the ADO.NET Entity Framework on the MSDN forums. Please see these posts for more information regarding these topics and to see the temporary workaround that I've come up with using XML and a SQL UDF.
回答4:
I had similar problem, and I got two ways to fix it.
- Intersect method
- join on IDs
To get values that are NOT in list, I used Except method OR left join.
Update
EntityFramework 6.2 runs the following query successfully:
var employeeIDs = Enumerable.Range(3, 5000);
var orders =
from order in Orders
where employeeIDs.Contains((int)order.EmployeeID)
select order;
回答5:
You could always partition your list of depts into smaller sets before you pass them as parameters to the IN statement generated by Linq. See here:
Divide a large IEnumerable into smaller IEnumerable of a fix amount of item
来源:https://stackoverflow.com/questions/656167/hitting-the-2100-parameter-limit-sql-server-when-using-contains