SHRINK DATABASE | SQL with Manoj

SQL DBA – Change RECOVERY mode & SHRINK all databases at once in SQL Server

July 17, 2020 2 comments

There are times when you are left with no or very less space in you SQL Server VM disks, and the main cause of this is not only the lot amount of data coming in but the heavy processing your database Server is doing, and thus filling up the entire log space.

SQL Server provides you some effective commands to shrink the database files which got inflated due to heavy processing and to make room for new data.

ALTER DATABASE <db_name> SET RECOVERY SIMPLE;

DBCC SHRINKFILE (N'<log_file_name>' , 100);

But this works with one database at a time, so what if you have lots of databases? It will be tiring and time consuming to visit each DB, get the database file names and apply the shrink command. Its even slow to do the same via SSMS GUI.

Note: Do not change the recovery mode in a PROD environment unless it is really required.

With the below T-SQL statements you can generate scripts for all the databases and can run to change all database settings at once:

-- Generate SQL Script to change Recovery mode to 'SIMPLE' for all DBs:
SELECT 
	'ALTER DATABASE [' + name + '] 
	 SET RECOVERY SIMPLE;' as SimpleRecovery4AllDBs
FROM sys.databases  
WHERE recovery_model_desc <> 'SIMPLE'

-- Generate SQL Script to Shrink log files of all DBs:
SELECT 
	'USE ' + DB_Name(database_id) + '; 
	 DBCC SHRINKFILE (N''' + name + ''' , 100);' as ShrinkAllDBs
FROM sys.master_files 
WHERE database_id > 4 and [type] = 1

Please let me know if you have any other way to do the same (and in more effective way) !!!

Categories: DBA Stuff, SQL DB Engine Tags: DBCC SHRINKDATABASE, DBCC SHRINKFILE, Recovery Mode, SHRINK DATABASE

Identify potential free space in Database files before shrinking – TSQL Query

April 27, 2014 3 comments

Today someone in office asked me:

"How can I know how much free space might be left in a Database to Shrink 
before actually Shrinking it?"

–> I told it is simple, go to SSMS, select Database -> Right click -> select Task -> select Shrink -> select either Database/File.

–> It will show you Available Free Space, of the whole Database or each mdf/ldf/ndf file(s).

–> He said he already knows it, his real ask was:

"what if you've hundreds of Databases and want to know the stats for each 
of them? Is there any SQL Query which can give you this stats, so that you can 
run it against each or all Database?"

I opened SQL Profiler, ran it against the instance and again performed all manual steps defined above to check the Free space. After the Shrink File pop-up window appeared I went back to the Profiler and stopped it, which threw me lot of typical SQL Queries generated by SQL Server DB engine. I searched and found the desired query that I was looking for. I slightly tweaked the query according to my needs and here it is:

USE [AdventureWorks2012]
GO

select 
	db_name()			AS [DatabaseName],
	s.name				AS [DB_File_Name],
	s.physical_name		AS [FileName],
	s.size * CONVERT(float,8) AS [TotalSize],
	CAST(CASE s.type WHEN 2 
			THEN s.size * CONVERT(float,8) 
			ELSE dfs.allocated_extent_page_count*convert(float,8) 
		END AS float)	AS [UsedSpace],
	CASE s.type WHEN 2 
		THEN 0 
		ELSE s.size * CONVERT(float,8) - dfs.allocated_extent_page_count*convert(float,8) 
	END					AS [AvailableFreeSpace] 
from sys.database_files AS s 
left outer join sys.dm_db_file_space_usage as dfs 
	ON dfs.database_id = db_id() 
	AND dfs.file_id = s.file_id
where (s.drop_lsn IS NULL)

–> Output: