Jack Li from MS SQL Server support blogged about the change in http://blogs.msdn.com/b/psssql/archive/2013/03/19/sql-server-2012-partitioned-table-statistics-update-behavior-change-when-rebuilding-index.aspx Here is what he said: In past versions, when you rebuild an index, you will get statistics update equivalent to FULLSCAN for free. This is true regardless if the table is partitioned table or not. But SQL Server 2012 changed the behavior for partitioned table. If a table is partitioned, ALTER INDEX REBUILD will only update statistics for that index with default sampling rate. In other words, it is no longer a FULLSCAN. This is documented in http://technet.microsoft.com/en-us/library/ms188388.aspx . But lots of users do not realized that. If you want fullscan, you will need to run UPDATE STATISTCS WITH FULLSCAN . This change was made because we started to support large number of partitions up to 15000 by default. Previous versions did support 15000 partition