See the breaking changes documentation for more details about how this can affect existing applications. AsEnumerable() // switches to LINQ to Objects To evaluate a predicate condition on the client as in the previous example, developers now need to explicitly switch evaluation of the query to LINQ to Objects: var specialCustomers = context.Customers When EF Core 3.x detects expressions that can't be translated anywhere else in the query, it throws a runtime exception. In EF Core 3.x, we've restricted client evaluation to only happen on the top-level projection (essentially, the last call to Select()). That may be acceptable if the database contains a small number of rows but can result in significant performance issues or even application failure if the database contains a large number of rows. Where(c => c.Name.StartsWith(n) & IsSpecialCustomer(c)) This type of client-side execution is desirable in some situations, but in many other cases it can result in inefficient queries.įor example, if EF Core 2.2 couldn't translate a predicate in a Where() call, it executed an SQL statement without a filter, transferred all the rows from the database, and then filtered them in-memory: var specialCustomers = context.Customers In previous versions, EF Core identified what portions of a query could be translated to SQL, and executed the rest of the query on the client. The most important design change has to do with how we handle LINQ expressions that cannot be converted to parameters or translated to SQL. The new LINQ provider is the foundation over which we'll be able to offer new query capabilities and performance improvements in future releases, without breaking existing applications and data providers. In EF Core 3.x, we rearchitected our LINQ provider to enable translating more query patterns into SQL, generating efficient queries in more cases, and preventing inefficient queries from going undetected.
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How to handle all those combinations is the main challenge for LINQ providers. NET language of choice, taking advantage of rich type information to offer IntelliSense and compile-time type checking.īut LINQ also enables you to write an unlimited number of complicated queries containing arbitrary expressions (method calls or operations). LINQ enables you to write database queries using your.
The following list includes the major new features in EF Core 3.xĪs a major release, EF Core 3.x also contains several breaking changes, which are API improvements that may have negative impact on existing applications.
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