When we shrink a SQL database through GUI we usually find the database never releases all the free space, It is always a good practice particularly in Production OLTP systems to shrink the database in small chunks so the data databse pages can be re-arranged and can free all unused space. The below TSQL will allow shrink a database file in increments until it reaches a target free space limit.
/*
This script is used to shrink a database file in
increments until it reaches a target free space limit.
Run this script in the database with the file to be shrunk.
1. Set @DBFileName to the name of database file to shrink.
2. Set @TargetFreeMB to the desired file free space in MB after shrink.
3. Set @ShrinkIncrementMB to the increment to shrink file by in MB
4. Run the script
*/
set nocount on
declare @DBFileName sysname
declare @TargetFreeMB int
declare @ShrinkIncrementMBint
-- Set Name of Database file to shrink
set @DBFileName = ''
-- Set Desired file free space in MB after shrink
set @TargetFreeMB = 0
-- Set Increment to shrink file by in MB
set @ShrinkIncrementMB= 100
-- Show Size, Space Used, Unused Space, and Name of all database files
select [FileSizeMB] = convert(numeric(10,2),round(a.size/128.,2)),
[UsedSpaceMB]= convert(numeric(10,2),round(fileproperty( a.name,'SpaceUsed')/128.,2)) ,
[UnusedSpaceMB]= convert(numeric(10,2),round((a.size-fileproperty( a.name,'SpaceUsed'))/128.,2)) ,
[DBFileName]= a.name
from sysfiles a
declare @sql varchar(8000)
declare @SizeMB float
declare @UsedMB float
-- Get current file size in MB
select @SizeMB = size/128. from sysfiles where name = @DBFileName
-- Get current space used in MB
select @UsedMB = fileproperty( @DBFileName,'SpaceUsed')/128.0
-- Loop until file at desired size
while @SizeMB > @UsedMB+@TargetFreeMB+@ShrinkIncrementMB
begin
set @sql = 'dbcc shrinkfile ( '+@DBFileName+', ' + convert(varchar(20),@SizeMB-@ShrinkIncrementMB)+' ) WITH NO_INFOMSGS'
print 'Start ' + @sql + ' at ' + convert(varchar(30),getdate(),121)
exec ( @sql )
print 'Done ' + @sql + ' at '+convert(varchar(30),getdate(),121)
-- Get current file size in MB
select @SizeMB = size/128. from sysfiles where name = @DBFileName
-- Get current space used in MB
select @UsedMB = fileproperty( @DBFileName,'SpaceUsed')/128.0
print 'SizeMB=' + convert(varchar(20),@SizeMB) + ' UsedMB=' + convert(varchar(20),@UsedMB)
end
select [EndFileSize] = @SizeMB, [EndUsedSpace] = @UsedMB, [DBFileName] = @DBFileName
