Monday, 18 January 2016

ASP.NET Tips #72 - If you don't need all the columns from your table, don't select them

Entity Framework is a great productivity booster for developers. Instead of writing tedious SQL statements, you just write code like this:

var products = db.Products.AsNoTracking().ToList();

A line like this is great if you only have a few columns in your products table or if you don't care much about performance or memory consumption. With this code, Entity Framework selects all the columns of the products table, but if your product table has 25 columns and you only need two of them, your database, network, and PC all run slower.

Do your users a favor and retrieve only the columns you need. If, for example, you just need the 'Id' and 'Name' fields, you could rewrite your statement like this:

var db.Products.Select(p => new {p.Id, p.Name}).AsNoTracking().ToList();

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