SELECT count(*)AS cached_pages_count, count(*)/ 128   'Size (Mb)'
    ,CASE database_id 
        WHEN  32767  THEN 'ResourceDb' 
        ELSE db_name(database_id) 
        END AS Database_name
FROM sys.dm_os_buffer_descriptors
GROUP BY db_name(database_id) ,database_id
ORDER BY cached_pages_count DESC

SELECT count(*)AS cached_pages_count , count(*)/ 128   'Size (Mb)',
    name ,index_id 
FROM sys.dm_os_buffer_descriptors AS bd 
    INNER JOIN 
    (
        SELECT object_name(object_id) AS name 
            ,index_id ,allocation_unit_id
        FROM sys.allocation_units AS au
            INNER JOIN sys.partitions AS p 
                ON au.container_id = p.hobt_id 
                    AND (au.type =  1  OR au.type =  3 )
        UNION ALL
        SELECT object_name(object_id) AS name   
            ,index_id, allocation_unit_id
        FROM sys.allocation_units AS au
            INNER JOIN sys.partitions AS p 
                ON au.container_id = p.hobt_id 
                    AND au.type =  2 
    ) AS obj 
        ON bd.allocation_unit_id = obj.allocation_unit_id
WHERE database_id = db_id()
GROUP BY name, index_id 
ORDER BY cached_pages_count DESC

select * from sys.dm_os_performance_counters 
where counter_name like 'T%Se%Memory%'

select * from sys.configurations where name like '%server memory%'