I found, that since SQL Server 2008 R2 there is a trace flag 2317 available. It turns on dynamical autoupdate statistics threshold, instead of default threshold of 20%. So, it greatly improves performance on systems with high tables (from 1 billion rows), because it could take a long time to reach 20% of rows modified. More of this here: http://support.microsoft.com/kb/2754171
Secondly, I found few unofficial topics, which says, that this trace flag is turned on by default since SQL Server 2012. But I can’t find any proof of this from vendor, Microsoft.
So, the question is: does anybody know anything about any changes on autoupdate stats default behavior since SQL Server 2012? Any link to BOL or MSDN would be appreciated.