IQueryable.All evaluate to false with predicate _ => true

[tomek-anuszkiewicz]

IQueryable.All evaluate to false with predicate _ => true

With https://github.com/dotnet/EntityFramework.Docs/tree/master/samples/core/GetStarted
Modify Program.cs like:

using (var db = new BloggingContext())
{
    db.Database.Migrate();

    // Create
    Console.WriteLine("Inserting a new blog");
    db.Add(new Blog { Url = "http://blogs.msdn.com/adonet" });
    db.SaveChanges();

    if (db.Blogs.ToList().All(_ => true) != db.Blogs.All(_ => true))
        throw new Exception("Why?");
}

Shouldn't Blogs.All(_ => true) evaluate to true like db.Blogs.ToList().All(_ => true)?

EF Core version: 5
Database provider: Sqlite
Target framework: NET5
Operating system: Windows
IDE: VS2019

[ajcvickers]

@tomek-anuszkiewicz I am not able to reproduce this. Copying that code into the GetStarted sample and running it does not generate an exception for me. Please attach a small, runnable project or post a small, runnable code listing that reproduces what you are seeing so that we can investigate.

[tomek-anuszkiewicz]

I'm confused. On my home PC it works as you said. But on my company notebook for db.Blogs.All(_ => true); I get:

 SELECT 0

It also the same for Azure App Service because there where the error was spotted.

Sample project:
GetStarted - Copy.zip

[ajcvickers]

Note for triage: this looks like a regression from 3.1 to 5.0. Logs from 3.1:

Inserting a new blog
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (2ms) [Parameters=[@p0='?' (Size = 28)], CommandType='Text', CommandTimeout='30']
      INSERT INTO "Blogs" ("Url")
      VALUES (@p0);
      SELECT "BlogId"
      FROM "Blogs"
      WHERE changes() = 1 AND "rowid" = last_insert_rowid();
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (0ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT "b"."BlogId", "b"."Url"
      FROM "Blogs" AS "b"
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (0ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT NOT EXISTS (
          SELECT 1
          FROM "Blogs" AS "b"
          WHERE 0 = 1)

Logs from 5.0:

Inserting a new blog
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (2ms) [Parameters=[@p0='?' (Size = 28)], CommandType='Text', CommandTimeout='30']
      INSERT INTO "Blogs" ("Url")
      VALUES (@p0);
      SELECT "BlogId"
      FROM "Blogs"
      WHERE changes() = 1 AND "rowid" = last_insert_rowid();
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (0ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT "b"."BlogId", "b"."Url"
      FROM "Blogs" AS "b"
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (0ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT 0
Unhandled exception. System.Exception: Why?
   at Program.Main() in /home/ajcvickers/Repros/GetStarted.-.Copy/GetStarted - Copy/Program.cs:line 25

Code:

class Program
    {
        static void Main()
        {
            using (var db = new BloggingContext())
            {
                db.Database.EnsureDeleted();
                db.Database.EnsureCreated();

                // Create
                Console.WriteLine("Inserting a new blog");
                db.Add(new Blog { Url = "http://blogs.msdn.com/adonet" });
                db.SaveChanges();

                var all = db.Blogs.ToList().All(_ => true);
                var all2 = db.Blogs.All(_ => true);
                
                if (all != all2)
                    throw new Exception("Why?");
            }
        }
    }

public class BloggingContext : DbContext
{
    private static ILoggerFactory ContextLoggerFactory
        => LoggerFactory.Create(b => b.AddConsole()); //.SetMinimumLevel(LogLevel.Information));

    public DbSet<Blog> Blogs { get; set; }
    public DbSet<Post> Posts { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder options)
        => options
            .UseLoggerFactory(ContextLoggerFactory)
            .UseSqlite("Data Source=blogging.db");
}

public class Blog
{
    public int BlogId { get; set; }
    public string Url { get; set; }

    public List<Post> Posts { get; } = new List<Post>();
}

public class Post
{
    public int PostId { get; set; }
    public string Title { get; set; }
    public string Content { get; set; }

    public int BlogId { get; set; }
    public Blog Blog { get; set; }
}

[smitpatel]

@maumar - This could be some optimization which works on 0 = 1 in predicate and removes it. Can you investigate?