Tramite T-SQL, in Microsoft SQL Server, è possibile determinare lo spazio usato da ogni tabella.
Lo script è il seguente:
DECLARE @KB bigint
DECLARE @MB bigint
DECLARE @GB bigint
DECLARE @TB bigint
SET @KB = 1024
SET @MB = @KB * 1024
SET @GB = @MB * 1024
SET @TB = @GB * 1024
 
--SELECT @KB AS [kB], @MB AS [MB], @GB AS [GB], @TB AS [TB]
 
DECLARE @Tables TABLE( 
        [name] sysname not null
       ,[schema] sysname not null
) 
 
DECLARE  @TableSize TABLE ( 
        [name] sysname 
       ,row_count INT
       ,reserved VARCHAR(50) 
       ,data VARCHAR(50)
       ,index_size VARCHAR(50) 
       ,unused VARCHAR(50)
       ,reservedInt bigint
       ,dataInt bigint
       ,index_sizeInt bigint
       ,unusedInt bigint
) 
 
INSERT INTO @Tables  
SELECT Table_Name, Table_Schema  
FROM information_schema.tables  
WHERE TABLE_TYPE = 'BASE TABLE'
 
DECLARE @name sysname  
DECLARE @schema sysname  
DECLARE @objName nvarchar(280)
 
DECLARE cur CURSOR FOR
SELECT [name], [schema]
FROM @Tables  
 
OPEN cur 
FETCH NEXT FROM cur INTO @name, @schema
WHILE @@FETCH_STATUS = 0  
BEGIN  
        SET @name = REPLACE(@name, ']',']]');  
        SET @schema = REPLACE(@schema, ']',']]');  
 
    set @objName = '[' + @schema + '].[' + @name + ']'
 
        IF EXISTS(SELECT id FROM sysobjects WHERE id = OBJECT_ID(@objName)) 
        BEGIN
               INSERT INTO @TableSize ([name],row_count,reserved,data,index_size,unused)
               EXEC sp_spaceused @objName, false
        END
        FETCH NEXT FROM cur INTO @name, @schema
END
CLOSE cur 
DEALLOCATE cur 
 
-- update int
UPDATE @TableSize SET
  reservedInt = charindex(' ', reserved)
  ,dataInt = charindex(' ', data)
  ,index_sizeInt = charindex(' ', index_size)
  ,unusedInt = charindex(' ', unused)
 
UPDATE @TableSize SET
  reservedInt = CASE
    WHEN reserved LIKE '% TB' THEN convert(bigint, substring(reserved,0, reservedInt) * @TB) 
    WHEN reserved LIKE '% GB' THEN convert(bigint, substring(reserved,0, reservedInt) * @GB) 
    WHEN reserved LIKE '% MB' THEN convert(bigint, substring(reserved,0, reservedInt) * @MB) 
    WHEN reserved LIKE '% KB' THEN convert(bigint, substring(reserved,0, reservedInt) * @kb) 
    ELSE convert(int, reserved) END
  ,dataInt = CASE
    WHEN data LIKE '% TB' THEN convert(bigint, substring(data,0, dataInt) * @TB) 
    WHEN data LIKE '% GB' THEN convert(bigint, substring(data,0, dataInt) * @GB) 
    WHEN data LIKE '% MB' THEN convert(bigint, substring(data,0, dataInt) * @MB) 
    WHEN data LIKE '% KB' THEN convert(bigint, substring(data,0, dataInt) * @kb) 
    ELSE convert(int, data) END
  ,index_sizeInt = CASE
    WHEN index_size LIKE '% TB' THEN convert(bigint, substring(index_size,0, index_sizeInt) * @TB) 
    WHEN index_size LIKE '% GB' THEN convert(bigint, substring(index_size,0, index_sizeInt) * @GB) 
    WHEN index_size LIKE '% MB' THEN convert(bigint, substring(index_size,0, index_sizeInt) * @MB) 
    WHEN index_size LIKE '% KB' THEN convert(bigint, substring(index_size,0, index_sizeInt) * @kb) 
    ELSE convert(int, index_size) END
  ,unusedInt = CASE
    WHEN unused LIKE '% TB' THEN convert(bigint, substring(unused,0, unusedInt) * @TB) 
    WHEN unused LIKE '% GB' THEN convert(bigint, substring(unused,0, unusedInt) * @GB) 
    WHEN unused LIKE '% MB' THEN convert(bigint, substring(unused,0, unusedInt) * @MB) 
    WHEN unused LIKE '% KB' THEN convert(bigint, substring(unused,0, unusedInt) * @kb) 
    ELSE convert(int, unused) END
--results
SELECT  A.[name], A.[row_count], A.[reserved], A.[data]
  , A.[index_size], A.[unused], B.[schema]
FROM @TableSize A  
  INNER JOIN @Tables B ON (A.[name] = B.[name] ) 
ORDER BY A.[reservedInt] desc, B.[schema], A.[name]
per ottenere informazioni sullo spazio occupato usa la store sp_spaceused.
L'output dello script è simile a questo:
name   row_count   reserved   data   index_size   unused   schema
backupfile	43794	22984 KB	22832 KB	144 KB	8 KB	dbo
backupset	19271	16016 KB	14824 KB	1120 KB	72 KB	dbo
sysmaintplan_logdetail	2298	7632 KB	7560 KB	8 KB	64 KB	dbo
backupmediafamily	19259	5712 KB	4376 KB	1216 KB	120 KB	dbo
backupmediaset	19259	3792 KB	2608 KB	1096 KB	88 KB	dbo
backupfilegroup	19348	3080 KB	2992 KB	16 KB	72 KB	dbo
...
Le colonne col suffisso 'Int contengono la dimensione in formato numerico, utile per gli ordinamenti.