Question

I am attempting to programmatically monitor the size of a SQL Server database, so that my admin section of my web app can report it, and I can use that to execute some cleanup SPs, to clear log files, etc.

I use the following code to calculate the size of the tables, per SO recommendation:

CREATE TABLE #t (name SYSNAME, rows CHAR(11), reserved VARCHAR(18), data VARCHAR(18), index_size VARCHAR(18), unused VARCHAR(18))EXEC sp_msforeachtable 'INSERT INTO #t EXEC sp_spaceused ''?'''-- SELECT * FROM #t ORDER BY name-- SELECT name, CONVERT(INT, SUBSTRING(data, 1, LEN(data)-3)) FROM #t ORDER BY nameSELECT SUM(CONVERT(INT, SUBSTRING(data, 1, LEN(data)-3))) FROM #tDROP TABLE #t 

When I run this against my small sample database, I get a total sum value of ~6.8 megabytes. When I look at the properties of my database, it shows 15.5 megabytes.

I have the following questions:
1. What else can make up the difference?
2. Can this difference be described as ‘overhead’, which will only grow at a fraction of the pace as other data grows (rough estimate is all I need for this).
3. Stored Procedures, Functions, Views, Triggers are in this ‘overhead’ space? Is there a way to calculate these?
4. Is there another way to get the WHOLE database size? I really just want a simple way to get the REAL size.

Answer 1

The difference, in my opinion, is due to the fact that the size you see in the ‘Properties’ page is calculated by querying the table .sys.database_files, which counts the number of 8KB pages allocated by each database file.

To obtain the same result, simply run the following query (SQL Server 2005):

 SELECT   SUM([size] * 8) / 1024  AS DB_Size -- Field 'size' contains the number of 8 KB pages contained in each file FROM   [db_name_here].sys.database_files 

More information about sys.database_files on MSDN website.

Hope this helps. 🙂

Diego