Entity Framework Core count does not have optimal performance

Question

I need to get the amount of records with a certain filter.

Theoretically this instruction:

_dbContext.People.Count (w => w.Type == 1);
         


        

Answer 1

It seems that there has been some problem with one of the early releases of Entity Framework Core. Unfortunately you have not specified exact version so I am not able to dig into EF source code to tell what exactly has gone wrong.

To test this scenario, I have installed the latest EF Core package and managed to get correct result.

Here is my test program:

And here is SQL what gets generated captured by SQL Server Profiler:

As you can see it matches all the expectations.

Here is the excerpt from packages.config file:

...

...

So, in your situation the only solution is to update to the latest package which is 1.1.0 at the time of writing this.