Question

When using the Entity Framework, does ESQL perform better than Linq to Entities?

I’d prefer to use Linq to Entities (mainly because of the strong-type checking), but some of my other team members are citing performance as a reason to use ESQL. I would like to get a full idea of the pro’s/con’s of using either method.

Answer 1

The most obvious differences are:

Linq to Entities is strongly typed code including nice query comprehension syntax. The fact that the “from” comes before the “select” allows IntelliSense to help you.

Entity SQL uses traditional string based queries with a more familiar SQL like syntax where the SELECT statement comes before the FROM. Because eSQL is string based, dynamic queries may be composed in a traditional way at run time using string manipulation.

The less obvious key difference is:

Linq to Entities allows you to change the shape or ‘project’ the results of your query into any shape you require with the “select new{… }” syntax. Anonymous types, new to C# 3.0, has allowed this.

Projection is not possible using Entity SQL as you must always return an ObjectQuery<T>. In some scenarios it is possible use ObjectQuery<object> however you must work around the fact that .Select always returns ObjectQuery<DbDataRecord>. See code below…

ObjectQuery<DbDataRecord> query = DynamicQuery(context,         'Products',         'it.ProductName = 'Chai'',         'it.ProductName, it.QuantityPerUnit');  public static ObjectQuery<DbDataRecord> DynamicQuery(MyContext context, string root, string selection, string projection) {     ObjectQuery<object> rootQuery = context.CreateQuery<object>(root);     ObjectQuery<object> filteredQuery = rootQuery.Where(selection);     ObjectQuery<DbDataRecord> result = filteredQuery.Select(projection);     return result; } 

There are other more subtle differences described by one of the team members in detail here and here.