LINQ .Select() is quite slow

Question

LINQ .Select() is quite slow

c# entity-framework entity-framework-core linq select

Question

I'm using EF Core. I have about 2500 records in database table Articles.

In management studio with EF compiled SQL I get result in few MS. In program about 30secs. .Select() is the issue. I don't know how to optimize it anymore.

1: before

List<Article> articles = await db.Articles.Select(x => new Article { Title = x.Title, Description = x.Description, Body = x.Body, Authors = x.Authors, PhotoAuthors = x.PhotoAuthors, Tags = x.Tags }).ToListAsync();

2: now

List<Article> articles = await db.Articles.FromSql("SELECT [x].[Title], [x].[Description], [x].[Body], [x].[Authors], [x].[PhotoAuthors], [x].[Tags] FROM[Articles] AS[x]").Select(x => new Article { Title = x.Title, Description = x.Description, Body = x.Body, Authors = x.Authors, PhotoAuthors = x.PhotoAuthors, Tags = x.Tags }).ToListAsync();

Result is still same :/

EDIT: Solution is to not use .ToList()

Using:

IQueryable<Article> articles = db.Articles.Select(x => new Article { Title = x.Title, Description = x.Description, Body = x.Body, Authors = x.Authors, PhotoAuthors = x.PhotoAuthors, Tags = x.Tags }).AsNoTracking();

IQueryable lose functions like .Split which I used later or Intersects.

user1085907

View more on Stack Overflow

gilliduck · Accepted Answer · 12/29/2017 4:43:56 PM

I think you're over thinking it.

var articles = db.Articles.ToList();

gets you a list of articles. If you really don't want to select extra fields, then you could do a

var articles = db.Articles.Select(x => new {...}).ToList();

but generally speaking you shouldn't see much of a difference between grabbing the entirety of vs just some of the headers. What you probably need is a .Where to limit things, but if you really need it all, just keep it simple.

LINQ .Select() is quite slow

Question

Fastest Entity Framework Extensions

Popular Answer

Performance

Expression Evaluator

Related