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

I know in one of the podcasts, Jeff mentioned that stackoverflow uses Linq-to-SQL

Answer 2

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.

Answer 3

While not directly addressing which ORM is faster as Ayende (NHibernate author) points out can be very easy to do wrong or at least slant the way you want it to, here are apps out there that are using ORMS as part of their applications.

Twitter is (was?) using Ruby on Rails (RoR) which uses an ORM. The 37 signal guys use RoR for their apps .... I know these aren't .Net but as mentioned by kuoson, L2S is employed by SO and there are alot of people out there using NHibernate like Jeffrey Palermo and Headspring. I wouldn't be surprised to find many recently developed web apps are employing an ORM.

Even if an ORM does cost you a hit on performance, most ORM's allow you to customize the SQL used when necessary. Most suggest using the ORM and then fixing bottlenecks as they arise. Additionally, a good ORM solves so much for you that writing your own DAL is becoming a much tougher sell these days.

Answer 4

jrista is right on. I just want to add that you should seriously consider LINQ to SQL. From both a simplicity and a performance standpoint it is the better technology (for now). It is very fast and reasonably capable out-of-the-box. If you want to further improve LINQ to SQL, check out the PLINQO framework.

PLINQO is a framework that sits around standard LINQ to SQL and adds a ton of features including some very elegant bulk operations and caching features. Best of all PLINQO adapts to changes in your database schema but preserves your custom code. Which is VERY slick and, in my opinion, the most valuable aspect.

Answer 5

Sure, reddit uses parts of SQLAlchemy (for reasons unknown I believe they rewrote most it :/). Most, if not all of the large Django websites use the ORM (including the former Pownce and Curse).

Answer 6

Worm supports caching and it is very useful feature for large sites. It reduce batch requests at times.

Answer 7

The really high traffic websites are in fact moving away from SQL databases altogether because with write-heavy workloads common in today's apps, it's nearly impossible to make them scale beyond one machine, ORM or no ORM. This has been dubbed the "NoSQL movement"

However, while this is a very fashionable topic, it's completely irrelevant for sites that don't have thousands of active concurrent users. And worrying about ORM performance is a similar matter: most sites are not in fact "high traffic" enough for an ORM to become a problem (unless grossly misimplemented or -applied).