LINQ to Dynamics CRM查询优化

Question

I'm working with a website that links into a Dynamics CRM Online. I'm new to both of these but find the best way to learn is to put yourself under pressure.

Anyway, I have the following LINQ query that I've built using LinqPad:

from m in py3_membershipSet
join c in ContactSet on m.py3_Member.Id equals c.ContactId 
where m.statuscode.Value == 1
orderby m.py3_name
select m

However, this gives an out of memory exception. It runs ok if I use Take(100) but I expect there to be about 1200 results to retrieve in total. Whether the memory issue is a LinqPad related problem I don't know but either way, I am assuming the above query isn't the most efficient way to pull these results.

I could really do with some help on making this more efficient, if it is as much of a memory hog as it appears via LinqPad.

Answer 1

An OutOfMemory exception ,

...is thrown when there is not enough memory to continue the execution of a program.

So I don't think it is anything in particular with the Linq you have written - apart from that it returning more data than your client can cope with. I suspect this is an issue more to do with your client than CRM or Linq.

This might be something do with LinqPad (not used it myself), have you tried running that script from a console app (to rule out any LinqPad issues)?

1200 doesn't sound like and awful lot of data, I often retrieve 1000~ records without issue but I have happily retrieved far more (5000~).

Paging might avoid the problem; Page Large Result Sets with LINQ .

Related reading: Troubleshooting Exceptions: System.OutOfMemoryException

Answer 2

Because the query does not know what fields will be needed later, all columns are returned from the entity when only the entity is specified in the select clause. In order to specify only the fields you will use, you must return a new object in the select clause, specifying the fields you want to use.

So instead of this:

from m in py3_membershipSet
join c in ContactSet on m.py3_Member.Id equals c.ContactId 
where m.statuscode.Value == 1
orderby m.py3_name
select m

Use this:

from m in py3_membershipSet
join c in ContactSet on m.py3_Member.Id equals c.ContactId 
where m.statuscode.Value == 1
orderby m.py3_name
select new py3_membership()
{
    py3_membershipid = m.py3_membershipid,
    py3_name = m.py3_name
}

Check out this post more details.

To Linq or not to Linq