The Lounge - CodeProject

Something more shocking, you know something that makes you go "ohm my!".

"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment
"Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst
"I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle

It's clearly your revenge after being involved into a fight recently, but remember: violence never solved anything $Shucks | :-\$

Non sequitur... a Prius doesn't have enough power.

Now that the i
Phones have facial recognition, if you put it in your back pocket does Siri say. Hello there,
Butt face??

CQ de W5ALT

Walt Fair, Jr., P. E.
Comport Computing
Specializing in Technical Engineering Software

I tried it out - mine said "Hello there Walt Fair Jr". Poke tongue | ;-P

I'm pretty sure I would not like to live in a world in which I would never be offended.

I am absolutely certain I don't want to live in a world in which you would never be offended.

Freedom doesn't mean the absence of things you don't like.

Dave

Well, Siri never metr me or my butt face, either!

CQ de W5ALT

Walt Fair, Jr., P. E.
Comport Computing
Specializing in Technical Engineering Software

Well that is even scarier then - she must have scraped it off the web somewhere! Laugh | :laugh:

So I have this project in .NET Core 2.0 with Entity Framework Core 2.0.
I have this entity which can be linked to other records of that same entity, let's say people.

So we have John, Bob, and Mary.
Mary can be linked to John and Bob.
My goal is simple, get all people that are not yet linked to the current person.
The LINQ query looks something like this:

C#

var result = context.Persons.Select(p => p.Name)
.Except(context.PersonLink.Where(pl => pl.PersonId == x)
    .Select(pl => pl.PersonLink.Name))
.OrderBy(n => n)
.Skip(a).Take(b).ToList();

And I'd except the SQL To look something like this:

SQL

SELECT Name
FROM Person
EXCEPT
SELECT Name
FROM PersonLink pl
JOIN Person p ON p.Id = pl.PersonLinkId
WHERE pl.PersonId = x
ORDER BY Name
OFFSET a FETCH NEXT b ROWS ONLY

Awfully easy.
Except EF Core messes this up.
It first gets the first set, then the second set, does the comparison in memory and, thus, the offset fetch in memory as well.
The result, in this case, is that the entire Person table is send to my client app, 8000 records, instead of the 100 I'm asking for.
It get's worse, let's say 7999 people are linked, I now have to get 15999 records to my client to end up with 1 Cry | :((

Checked my code, my DbContext, Entity classes, re-read my LINQ query a thousand times, even tried it in EF6, but everything seemed fine.

Then I stumbled upon Query: Translate IQueryable.Concat/Union/Intersect/Except/etc. to server · Issue #6812 · aspnet/EntityFrameworkCore · GitHub[^]
It seems EF Core simply doesn't translate set operators to SQL WTF | :WTF:

Of course we're only dealing with sets here, so there's no real need to support any set operators Sigh | :sigh:

I know .NET Core and EF Core aren't exactly proven technologies yet, but come on... WTF | :WTF:

Best,
Sander

Continuous Integration,
Delivery, and Deployment
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