关于avg_fragmentation_in_percent ，可以参考这里更加权威的解释
http://connect.microsoft.com/SQLServer/feedback/details/690672/avg-fragmentation-in-percent-is-not-precise#details
Thanks for contacting SQL Server team with your question. As seen by you, the SQL Server does not consider data to be fragmented if the extents are not logically contiguous. In other words, if the two logically adjacent pages in an index correspont to the last page in extent X and the first page of extent Y respectively, SQL Server does not consider this to be fragmented. Suppose you rebuild an index on a filegroup that has multiple objects, it is unlikel that you will get physically contiguos extents. show extent fragementation for HEAPs but not for indexes.However, you can use DBCC extentinfo command to look at the extents allocatd to the object. Wondering if you have read the blogs related to fragmentation. Here is the link
http://blogs.msdn.com/b/sqlserverstorageengine/archive/2008/03/01/example-data-fragmentation-with-insert-updates-measuring-it-and-fixing-it.aspx
avg_fragmentation
------解决方案--------------------
睇唔系几清楚下哦~