sys.dm_db_index_physical_stats has some modes. limited, sampled, detailed
when using limited , some information are null in the result. using sampled and detailed all results come out.
I found in 'sampled' mode, avg_fragmentaion_in_percent and avg_page_space_used_in_percent are matched with using management stutio to view. however the row_count is littlebit different
in Detailed mode. avg_fragmentaion_in_percent and avg_page_space_used_in_percent are not match and row_count also not match
why this happen?