DBCC DBREINDEX in MS SQL Server 2008 We have done DBCC DBREINDEX for our production database which size is about 300 gb, it was running for 12+ hours, but i found that DBCC DBREINDEX is obsolete and recommended approach is using ALTER INDEX command with rebuild, also, we have performance problems right now with database, could it be related to using old method for reindexing ? We have MS SQL Server 2008 (11.2)
As it states on the ALTER INDEX documentation, using ALTER INDEX ...REBUILD is equivalent to DBCC DBREINDEX.

ALTER INDEX has far more functionality in terms of other arguments and DBCC DBREINDEX is deprecated, however the performance issues you face should not  be related to using the old method of re-indexing.