Date: 17 Nov 2010
Retrieves the number of pages with database content in the SQL Server Buffer Pool. Utilizes the dmv sys.dm_os_performance_counters, which is an upgrade to the SQL 2000 SysPerfInfo function.
I found this useful in the past when tracing memory and performance problems in a multi-instance SQL Server environment where an XML index was being used inappropriately to service a range type query. I wrote a small batch job to capture snapshots of this counter regularly and helped to determine that the entire index (50GB) was being loaded into cache each morning and then aged out of cache overnight.