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Entity Framework For DBAs
The document provides an overview of Entity Framework (EF), an Object-Relational Mapping (ORM) framework for .NET applications, highlighting its functionality, versions, and developer productivity benefits. It emphasizes the importance of proper database design and considerations for ORM-generated databases, alongside potential performance issues related to LINQ queries. Additionally, the document references various resources for further learning and tips for effective usage of EF.
Entity Framework For DBAs
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- 3. • What isEntity Framework? • How does Entity Framework work? • Why do developers like it? • What should you, the DBA, be looking for in an Entity Framework project.
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- 9. • Object RelationalMapping • Converts pragmatic objects into a relational database. – Hibernate (Java) – Active Record (Ruby) Objects Mapping Data
- 10. • ORM for.NET Applications • Allows the developer to: – Generate databases – Save object data to a database – Generate DDL scripts from object changes – Generate SQL for data retrieval • All done with very minimal code.
- 13. using (conn =new SqlConnection(connectString)) { conn.Open(); DbCommand cmd = conn.CreateCommand(); cmd.Connection = conn; cmd.CommandText = "SELECT Name, AccountNumber FROM sales.Store"; dbReader = cmd.ExecuteReader(); // do something cmd.Dispose(); conn.Close(); }
- 14. var stores = context.Stores.Include(c=> c.Customers);
- 15. Lovingly stolen fromProgramming Entity Framework: Code First by Julie Lerman and Rowan Miller page 9.
- 16. Design Centric CodeCentric New Database Existing Database Model First Create .edmx model in designer Generate DB from .edmx Classes auto-generate from .edmx Database First Reverse engineer .edmx model Classes auto-generate from .edmx Code First Define classes & mapping in code Database auto-created at runtime Code First Define classes & mapping in code Adapted from Programming Entity Framework: Code First by Julie Learman and Rowan Miller page 3.
- 17. • v1.0 -.NET 3.5 • V4.0 - .NET 4.0. - Lazy Loading, POCO, Perf Enhancements • v4.2 – Bug Fixes - Semantic versioning • v4.3 – Code First • V5.0 – .NET 4.5 - ENums, table-valued functions, Spatial Data Types • V6.0 – Async Support, Connection Resiliency
- 18. • Developer workswith objects. • Focus on Business Domain (objects) not DB, Connections, commands, etc. • Developer Productivity • No need to write SQL or CRUD commands
- 19. • Microsoft ismaking minimal investment in ADO.Net. • LINQ to SQL is essentially dead • EF is now recommended for Data Access • EF is now open-source software
- 20. • Database Generation •N + 1 Problem • Murder on the Index Express • Searching • Caching
- 21. • EF cangenerate databases • EF Migrations can even generate database updates and roll-forward or rollback. • I don’t recommend blindly generating any database from any ORM. • DEMO
- 22. • Things tolook for in a ORM generated DB – Normalization – Relationships (They may not exist but should) – Proper Types (NVarchar / BigInt are the exception) – Indexes on FKs – Primary Keys – Table Naming Convention (Singular vs. Plural) – Object Naming (such as Keys and Indexes)
- 23. • Occurs whenobject have a 1 : M relationship. Store Customer
- 24. • Use theIncludes feature • Use a Stored Procedure
- 25. • By default,the a LINQ query will return ALL attributes in an object. • Essentially, it’s performing a SELECT * against the table. • Key lookup city. • To fix use LINQ projections.
- 26. • Using theCONTAINS function in a LINQ query creates a LIKE clause. • LIKE has been know to decimate performance. • We can fix this by using a Full Text Search
- 27. • Complex LINQqueries can generate some awful SQL. • Cut your losses and replace the LINQ query with a SQL one.
- 28. • This problemhas been mostly fixed in EF 4.1+. • But you can still run into problems with Code First.
- 29. • Use aCaching Layer – Redis – ASP.Net has a caching library built in. • Use a EF Profiler – Hibernating Rhinos – MiniProfiler
- 31. • Julie Lerman’sBlog http://thedatafarm.com/blog/ • Rowan Miller’s Blog http://romiller.com • Arthur Vicker’s Blog http://blog.oneunicorn.com • #efhelp on twitter • StackOverflow (of course) • PluralSite – Julie Lerman’s EF videos
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