Programmatically determine available free space on a database?

Question

Ok, I have tried searching around for this answer, but with no luck. I have about 50 databases on our SQL Server at work that I have to check almost every day to see if any space can be freed up via shrinking. Our drives tend to fill up a lot, so this is why it is an almost daily task.

Is there a quick way to check what databases actually have free space available? Does anyone know of a system/custom stored procedure or system view that can generate a list of every database and how much free space is available to be shrunk on that database?

By the way, using sql server 2005.

Answer 1

Probably something in WMI or SQL views. But I gotta ask - how does the cost of your time poking around with this every day compare to buying some disk drives?

Answer 2

Im not sure, if even SQL server knows this, before the shrink is done :-)

Answer 3

The answer is not to worry about how much free space there is in the databases, and instead run a nightly or weekly maintenance task that runs compaction. Odds are you're not compacting your log files (this is where I usually had the most growth).

Run a full backup, then run a transaction log backup with TRUNCATE_ONLY and once that completes, run DBCC SHRINKFILE() on your logfiles and databases.

Then you only have to monitor total available diskspace, and not individual database growth.

SQL Server Shrink Database. You absolutely HAVE to perform a full backup and a transaction log backup before this will work.

You can get information about the individual files loaded by running 'select * from master.dbo.sysdatabases' and the run 'select * from [dbname]..sysfiles'. I'm not 100%, I haven't touch a SQL Server instance in almost a year, sysfiles might be in the 'master' database.

Answer 4

---

Run sp_spacedused for each database:

--temporary table to hold database names
CREATE TABLE #Databases (name varchar(255))

INSERT INTO #Databases
SELECT name FROM master..sysdatabases

DECLARE abc CURSOR FOR
   SELECT name FROM #Databases

DECLARE @name varchar(255)
DECLARE @sql nvarchar(1024)

OPEN abc

FETCH NEXT FROM abc INTO @name

WHILE @@FETCH_STATUS = 0 
BEGIN
   --build sql to switch to that database...
   SET @sql = 'USE '+@name
   PRINT @sql
   EXECUTE (@sql)

   --and run spaceused on it
   SET @sql = 'EXECUTE sp_spaceused @UpdateUsage=True'
   PRINT @sql
   EXECUTE (@sql)

   FETCH NEXT FROM ABC INTO @name
END

CLOSE abc
DEALLOCATE abc
DROP TABLE #Databases

---

Sample singular results

Execute T-SQL:

USE CMSFintrac
EXECUTE sp_spaceused @UpdateUsage=True

Results:

database_name: CMSFintrac
database_size:     85.13 MB
unallocated_space: 15.41 MB

reserved:         70,368 KB (68.7 MB)
data:             42,944 KB (41.9 MB)
index_size:       24,200 KB (23.6 MB)
unused:            3,224 KB ( 3.1 MB)

Shrink:

DBCC SHRINKDATABASE (CMSFintrac)

Check space again:

EXECUTE sp_spaceused @UpdateUsage=True

Results:

database_name: CMSFintrac
database_size:     69.81 MB
unallocated_space:  0.20 MB

reserved:         70,256 KB (68.6 MB)
data:             43,024 KB (42.0 MB)
index_size:       24,200 KB (23.6 MB)
unused:            3,032 KB ( 3.0 MB)

Answer 5

You can use either sp_spaceused and consume its result, or you can look yourself in the sys.allocations_units table and count the total used pages. You shouldn't look at 'database' level but at file level because some might have multiple NDFs. Start with sys.database_files to see all files in the database files. The size column will contain the total number of pages in the database. The sum up the total pages from sys.allocation_units to get the used pages:

with sum_au as (
select data_space_id
    , sum(total_pages) as total_pages
    from sys.allocation_units au 
    group by data_space_id)
select ds.name
    , df.size
    , total_pages as in_use 
    from sys.database_files df
    join sys.data_spaces ds on df.data_space_id = ds.data_space_id
    join sum_au au on au.data_space_id = ds.data_space_id