How To Estimate Data Utilization

USE master;
GO
 
/* 
    This will give you an approximation of how much data is being utilized on a server.
    Since the data is only valid as of the last server reboot, we should start off with
    an idea of how much data we've accrued.  
*/
 
/* Find out when the server was last rebooted */
-- 2008
SELECT sqlserver_start_time FROM sys.dm_os_sys_info;
-- 2005
SELECT create_date FROM sys.databases WHERE name = 'tempdb';
 
 
/* Create a temporary table to hold our data, since we're going to iterate through databases */
IF OBJECT_ID('tempdb..#Results') IS NOT NULL
    DROP TABLE #Results;
 
CREATE TABLE #Results
(
      databaseName  NVARCHAR(128)
    , tableName     NVARCHAR(128)
    , indexID       INT
    , records       BIGINT
    , activity      BIGINT
    , totalPages    BIGINT
);
 
/*  
    sp_foreachdb was written by SQL MVP Aaron Bertrand and can be downloaded 
    at http://www.mssqltips.com/sqlservertip/2201/making-a-more-reliable-and-flexible-spmsforeachdb/
    Alternatively, you can also use sys.sp_MSforeachdb
*/
--EXECUTE master.dbo.sp_foreachdb
EXECUTE sys.sp_MSforeachdb
'   USE ?; 
 
    -- You can gleam a lot of information about historical data usage from partitions
    -- but for now, we will just roll up any partitions we may have
    WITH myCTE AS
    (
        SELECT p.[object_id] AS objectID
            , p.index_id
            , SUM(p.[rows]) AS records
            , SUM(au.total_pages) AS totalPages
        FROM sys.partitions AS p WITH (NOLOCK)
        JOIN sys.allocation_units AS au WITH (NOLOCK)
            ON p.hobt_id = au.container_id
        GROUP BY p.[object_id] 
            , p.index_id
    )
 
    -- Grab all tables and join to our usage stats DMV
    INSERT INTO #Results
    SELECT DB_NAME() AS databaseName
        , t.name
        , x.index_id
        , MAX(x.records) AS records
        , ISNULL(SUM(us.user_lookups + us.user_scans + us.user_seeks), 0) AS activity
        , SUM(x.totalPages) AS totalPages
    FROM sys.tables AS t WITH (NOLOCK)
    JOIN myCTE AS x
        ON t.[object_id] = x.objectID
    LEFT JOIN sys.dm_db_index_usage_stats AS us WITH (NOLOCK)
        ON us.[object_id] = x.objectID
        AND us.index_id = x.index_id
        AND us.database_id = DB_ID()
    GROUP BY t.name
    , x.index_id;'
 
/* Because we're looping through databases, make sure we're not missing any major ones */
SELECT * FROM sys.databases WHERE name NOT IN (SELECT databaseName FROM #Results);
 
/* Retrieve actual % data utilization, which is performed at the index level */
SELECT databaseName
    , SUM(queriedPages) AS TotalQueriedPages
    , SUM(totalPages) AS TotalPages
    , CAST(SUM(queriedPages) AS FLOAT) / REPLACE(SUM(totalPages), 0, 1) AS '%DataUtil'
FROM (
    SELECT databaseName
        , tableName
        , indexID
        , CASE -- If we have any activity at all on an index, count it as activity
            WHEN activity = 0 THEN 0.0
            ELSE totalPages
          END AS queriedPages
        , totalPages
    FROM #Results
    WHERE databaseName NOT IN ('master', 'tempdb', 'msdb', 'model')
) x
GROUP BY databaseName
ORDER BY databaseName;
 
/* Retrieve % content utilization, which is performed at the table level */
SELECT databaseName
    , SUM(queriedPages) AS TotalQueriedPages
    , SUM(totalPages) AS TotalPages
    , CAST(SUM(queriedPages) AS FLOAT) / REPLACE(SUM(totalPages), 0, 1) AS '%ContentUtil'
FROM (
    SELECT databaseName
        , tableName
        , MAX(records) AS records
        , CASE WHEN SUM(activity) > 0 THEN SUM(totalPages) ELSE 0 END AS queriedPages
        , SUM(totalPages) AS totalPages
    FROM #Results
    WHERE databaseName NOT IN ('master', 'tempdb', 'msdb', 'model')
    GROUP BY databaseName
        , tableName
) x
GROUP BY databaseName
ORDER BY databaseName;

databaseName               TotalQueriedPages   TotalPages           %DataUtil
-------------------------- ------------------- -------------------- ----------------------
Database1 		   127618701           130607247            0.969619893356378
Database2 		   567188              1614958              0.351209133612143
Database3 		   34269036            34579469             0.991022620966216
Database4 		   137970594           170733391            0.803399928206158
Database5 		   74632930            101543575            0.66909214627557
Database6 		   55809933            72884205             0.765734157938039
Database7 		   560810026           620609815            0.902175272517656
 
databaseName               TotalQueriedPages   TotalPages           %ContentUtil
-------------------------- ------------------- -------------------- ----------------------
Database1 		   127763715           130607247            0.970721679051682
Database2 		   571125              1614958              0.353646967908763
Database3 		   34269036            34579469             0.991022620966216
Database4 		   137970921           170733391            0.803399928206158
Database5 		   96144726            101543575            0.861947682777784
Database6 		   72269666            72884205             0.991568146820268
Database7 		   620525938           620609815            0.998240279711804