mike.bishop (6/17/2008)
In the sys.dm_db_index_usage_stats DMV the field user_lookups is the total number of bookmark lookups. Correct?
Correct
Either way my question is why do bookmark lookups occur on a clustered index?
They don't occur on the clustered index. They occur to the clustered index.
A lookup occurs when SQL has used one of the nonclustered indexes to find rows,but it needs columns that are not in that nonclustered index, so it does a lookup to the clustered index to find the missing columns.
Make more sense?
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability