Memory utilization per database - SQL Server
SELECT db = DB_NAME(t.dbid), plan_cache_kb = SUM(size_in_bytes/1024) 
FROM sys.dm_exec_cached_plans AS p
CROSS APPLY sys.dm_exec_sql_text(p.plan_handle) AS t
WHERE t.dbid &lt; 32767
GROUP BY t.dbid
ORDER BY plan_cache_kb DESC;


This tip I wrote on mssqltips.com might be useful as well if you want to dig deeper into buffer usage.