How does the sys.objects Catalog View pull from itself?

Question

I'm using this stored procedure called OBJECT_DEFINITION as was suggested. It's helping me wrap my head around the SQL Server system. However, there is one area that I can't yet figure out. On this one table sys.objects, you'll see it pulls from itself.

1> SELECT OBJECT_DEFINITION(OBJECT_ID('sys.objects'))
2> GO

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
CREATE VIEW sys.objects AS
    SELECT name, 
      .. stuff.
    FROM sys.objects$

Now I'm totally lost how is sys.objects selecting from sys.objects$ what is sys.objects$. Thinking there may be a table of the same name, I first tried to create a table and a view by the same name, but I can't do that. I get (f is the name I picked). You can't do this in any database I've ever used.

Msg 2714, Level 16, State 3, Server x230, Procedure f, Line 1
There is already an object named 'f' in the database.

Microsoft docs sys.objects only as a Catalog View, it's not listed as a Base Table

The counterpart Catalog View, sys.system_objects pulls from the Base Table sys.sysschobjs, and OBJECT_DEFINITION clearly shows that.

My guess is that the SQL here isn't the actually SQL the view is executing, but some kind of comment or description on it: meta-data of sort, and that it's bugged. But, I could be totally off.

Answer 1

sys.objects is not a table, it is a system catalog view. The definition shown in the question even shows Create VIEW .... Also, sys.objects is not the same thing as sys.objects$:

1. You cannot select from sys.objects$ on a regular connection. You need to be on a DAC connection, though not necessarily in Single-User mode, to SELECT from it.

2. They don't have the same number of columns. Just connect to the DAC connection and run the following:

   SELECT TOP (1) * FROM sys.objects;
   GO
   SELECT TOP (1) * FROM sys.objects$;
   GO
   

sys.objects$ must be an internal catalog view since the underlying fields in sys.objects (no trailing $) come from these tables: sysschobjs, syssingleobjrefs, syspalnames.