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Left outer join in Entity Framework

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This evening I heard someone say that Left Outer Joins are not possible in Entity Framework or perhaps Left Outer Joins are possible, but they bring in all the data and then filter out the right table.

I felt an urge to argue, but I resisted. I thought I would investigate before I waste time. I came up with some articles pretty quickly.

  1. Left Outer Join in LINQ
  2. Left Outer Join using Inverse Navigation Property
  3. DefiningQuery Element
  4. Left Outer Join in LINQ to SQL
  5. LINQ to Entities with Multiple Left Outer Joins

I am sure these should resolve all questions related to Left Outer Joins.

Now about the performance and the question about how the data is brought, I am pretty sure we can prove that LINQ Queries all support deferred execution. But we can always prove that using the SQL Query Profiler.

Hope this helps.