juniorEntity Framework
What is the difference between IEnumerable and IQueryable in EF?
Updated Apr 28, 2026
Short answer
IQueryable executes queries on the server (database). IEnumerable executes queries in memory (client-side).
Deep explanation
When using IQueryable, LINQ commands are translated into SQL and executed efficiently by the DB engine. If you cast a DbSet to IEnumerable or call .ToList() before filtering, the entire table is pulled into memory, and filtering happens in C#.
Real-world example
Using IQueryable to apply pagination (.Skip().Take()) so the database only returns the 10 rows needed for the current page.
Common mistakes
- Calling .ToList() too early in a query chain, crashing the application due to out-of-memory exceptions when querying large tables.
Follow-up questions
- What interface does IQueryable inherit from?