How to optimize IPaginatedList?

Question

ASP.NET

Hi all. Faced such a problem. Used on EF 6 + IPaginationList project. The implementation has a field that receives the number of records Count(). The request hangs on this line of code.

public IPaginatedList<T> Apply<T>(IEnumerable<T> source)
        {
            var totalRecords = source.Count();
        .....

There are 250 thousand records in the database. Can it be optimized somehow? Thanks

Answer 1

You have an IEnumerable method as input, which causes C# to enumerate the data source (SELECT * FROM source).
To instead generate a request for a quantity, you need to receive an IQueryable as an input. Then a query like SELECT count(*) FROM source will be generated.

Answer 2

maybe make a query at the database level