RavenDB Lazy Requests

In my previous post, I discussed the server side implementation of lazy requests / Multi GET. The ability to submit several requests to the server in a single round trip. RavenDB has always supported the ability to perform multiple write operations in a single batch, but now we have the reverse functionality the ability to make several reads at one. (The natural progression, the ability to make several read/write operations in a single batch will not be supported).

As it turned out, it was actually pretty hard to do, and require us to do some pretty deep refactoring to the way we were executing our requests, but in the end it is here and it is working. Here are a few examples of how it looks line from the client API point of view:

var lazyUser = session.Advanced.Lazily.Load<User>("users/ayende");
var lazyPosts = session.Query<Posts>().Take(30).Lazily();

And up until now, there is actually nothing being sent to the server. The result of those two calls are Lazy<User> and Lazy<IEnumerable<Post>>, respectively.

The reason that we are using Lazy<T> in this manner is that we want to make it very explicit when you are actually evaluating the lazy request. All the lazy requests will be sent to the server in a single roundtrip the first time that any of the lazy instances are evaluated, or you can force this to happen by calling:

session.Advanced.Eagerly.ExecuteAllPendingLazyOperations();

In order to increase the speed even more, on the server side, we are actually going to process all of those queries in parallel. So you get several factors that would speed up your application:

• Only a single remote call is made.
• All of the queries are actually handled in parallel on the server side.

And the best part, you usually don’t really have to think about it. If you use the Lazy API, it just works.