Do Large High-Traffic Websites use ORMs?

Question

I have finally decided to go with the Entity Framework since it has the best performance out of all the ORMs. But before I start reading and writing code I just want to know if there are any high traffic websites out there that use ORMs.

Answer 1

Currently, the released version of EF, v1.0 in .NET 3.5, has terrible performance. I did extensive testing and had several long email discussions with Microsoft on the subject over a year ago when it was first released. EF's current efficiency has a LOT to be desired, and in many cases, can generate absolutely atrocious SQL queries that decimate your performance.

Entity Framework v4.0 in .NET 4.0 is a LOT better. They have fixed most, if not all, of the poor SQL generation issues that plague EF v1.0 (including the issues I presented to them a year ago.) Whether EF v4.0 has the best performance is really yet to be seen. It is more complex than LINQ to SQL, as it provides much greater flexibility. As a release version is not yet available, its impossible to say whether EF v4.0 will be the fastest or not.

An objective answer to this would require an objective, unbiased comparison between the major ORM contendors, such as EF, LINQ to SQL, nHibernate (preferably with a LINQ provider), LLBLGen, and even some of the newcommers, such as Telerik's ORM, Subsonic and the like.

As for large-scale, high-volume production systems that use ORM's. I would suggest looking at StackOverflow.com itself, which uses LINQ to SQL. SO has become one of, if not the, top programmer communities on the Internet. Definitely high volume here, and this site performs wonderfully. As for other sites, I couldn't really say. The internal implementation details of most major web applications are generally a mystery. Most uses of ORM's that I know of are also for internal, enterprise systems. Financial systems, health care, etc. Object Databases are also used in the same kinds of systems, although they are much less frequent. I would so some searches for ORM use and high volume web sites.

One thing to note in your search. Make sure the reviews you find are current. The ORM scene has changed a LOT in the last two years. Performance, efficiency, capabilities, RDBMS tuning capability of dynamic SQL, etc. have all improved significantly since ORM's were first created around a decade ago.