Entity Framework Core generates two select queries for one-to-many relationship

问题

I'm building an EF Core provider for the Google Spanner db. I've bumped with an issue when trying to select an entity with one to many relationship.

For example, lets say I have the following entities:

public class Player
{
    public string PlayerId { get; set;}

    public string Name { get; set;}

    public List<Game> Games { get; set;}

}

public class Game
{
    public string GameId { get; set; }

    public string PlayerId { get; set; }
    public Player Player { get; set;}
}

Each Game is related to one Player and each Player has many games...

When running the following query:

ctx.Players
.Include(p => p.Games)
.Where(p => p.PlayerId == "123")
.Select(p => new {
    PlayerId = p.PlayerId,
    Games = p.Games
});

Two select queries are constructed and executed separately against the DB:

SELECT "p"."PlayerId" FROM "Players" AS "p" WHERE "p"."PlayerId" = '123'
SELECT "p0"."GameId" FROM "Games" AS "p0" WHERE '123' = "p0"."PlayerId"

Is it a known issue? Can I control the SelectExpression to be created only as one select (using join...)?

来源：https://stackoverflow.com/questions/43472071/entity-framework-core-generates-two-select-queries-for-one-to-many-relationship