Fixing a Bug: DBCC CHECKDB data purity checks are skipped for master and model

Fellow MVP Paul Randal just blogged about an issue he has discovered with how the master and model databases are created in SQL Server 2005, SQL Server 2008, SQL Server 2008 R2, and SQL Server 2012. I just checked, and the same issue is present in SQL Server 2014 CTP1 (Build 11.0.9120).

Here is a more heavily commented version of Paul’s code to detect and fix the issue (that is also easier to copy and paste).  Please read Paul’s post for more details and background.

-- Fixing a Bug: DBCC CHECKDB data purity checks are skipped for master and model
-- By: Paul Randal
-- Posted on: August 29, 2013 1:15 pm 
-- http://www.sqlskills.com/blogs/paul/bug-dbcc-checkdb-data-purity-checks-are-skipped-for-master-and-model/

-- Turn on a session-level trace flag
DBCC TRACEON (3604); 

-- Look for the value of dbi_dbccFlags = 0. We want it to be dbi_dbccFlags = 2
DBCC DBINFO (N'master'); 
GO 
DBCC DBINFO (N'model'); 
GO 


-- This will set the value for dbi_dbccFlags correctly as part of running DBCC CHECKDB
DBCC CHECKDB (N'master') WITH DATA_PURITY, NO_INFOMSGS; 
GO
DBCC CHECKDB (N'model') WITH DATA_PURITY, NO_INFOMSGS; 
GO

-- Look for the value of dbi_dbccFlags = 2
DBCC DBINFO (N'master'); 
GO 
DBCC DBINFO (N'model'); 
GO 

-- Turn off the trace flag (even though it is just a session trace flag)
DBCC TRACEOFF (3604);