On Entity Framework And SQL Server

Specificity


I know there are other ORMs in the world, but since my working life is spent performance fixing SQL Server, I end up seeing Entity Framework the most.

This isn’t going to be an Entity Framework bash-fest (that’s what Twitter is for), it’s more a critique of the way developers blindly trust this abstraction layer to always do the smart and sensible thing.

After all, I’ve seen applications using Entity Framework quite successfully. Part of what made it successful was the developers being comfortable with the database, figuring out how what they do with code gets translated into a query, and when that ends up going terribly long.

One of  the big lightbulb moments they had was realizing that maybe doing it all in one big query isn’t always the best option.

Until It Doesn’t


On small databases, perhaps with uncomplicated schema and application requirements, you can get by without giving much of a care about these things.

However, as databases grow up, more tables get added, and all that, you need to start paying more attention. I’ve said it before: abstraction isn’t magic, and that holds true for Entity Framework, too.

I totally understand: you might not know anything about databases, might not  have any interest in learning more about databases, and your job is to focus on the code to develop new features. Because of that, you put your faith and trust into Entity Framework to do things the best, most correct way.

That isn’t always what happens, though. It might work, but it might not work well. Not being an Entity Framework expert, I’m not always sure if the disconnect is in the way Entity Framework is designed, or in the way the developer used it.

Funny Valentine


For transactional queries, you’ll generally be okay so long as you obey common database decency rules around table and index design.

What is usually overly-ambitious is reporting and dashboard population queries. They’re often interpreted poorly, with dozens of left joins and nested derived tables.

And look, no, I don’t expect someone coding those types of queries in Entity Framework to be able to write better T-SQL queries. They probably have even less training and experience there. I’m basically repeating myself: abstraction isn’t magic.

If you’re going to work heavily with Entity Framework code that hits SQL Server, you need to:

  • Get into databases
  • Get someone who’s into databases

You need someone who can get in there, find problem queries, review indexes, and help track down which sections of the code generate them.

Whether some portions of the application need to be replaced with stored procedures, or you write custom SQL that can take advantage of a different approach to accessing the data, you need someone with the skills to write that T-SQL well, or you’ll just end up with the same problem in a different way.

Thanks for reading!



3 thoughts on “On Entity Framework And SQL Server

  1. So true. Except that ORM vendors tell them to forget about databas – “That’s what ORM is for! Be cool, develope code! Heave-ho! Want to smash DBA-shaped piñata anyone?!”

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