Symptoms
Assume that you have a table that contains a large object (LOB) column in Microsoft SQL Server 2008, SQL Server 2008 R2, SQL Server 2012, or SQL Server 2014. When you update the LOB column with smaller size of LOB data and try to reclaim the unused space by using the following methods:
-
DBCC SHRINKDATABASE / DBCC SHRINKFILE
-
ALTER INDEX REORGANIZE WITH (LOB_COMPACTION = ON)
In this situation, the unused space cannot be reclaimed.
Resolution
The issue was first fixed in the following cumulative update of SQL Server.
Cumulative Update 2 for SQL Server 2012 SP2 /en-us/help/2983175
Cumulative Update 11 for SQL Server 2012 SP1 /en-us/help/2975396
Cumulative Update 13 for SQL Server 2008 R2 SP2 /en-us/help/2967540
Cumulative Update 2 for SQL Server 2014 /en-us/help/2967546
Cumulative Update 17 for SQL Server 2008 SP3 /en-us/help/2958696
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:
Workaround
To work around this issue, use the following workarounds:
-
Export all the rows to a new table and move the rows back. This reorganizes the LOB data and release the unused space.
-
Use DBCC SHRINKFILE with EMPTYFILE option to move all the data to a newly added data file and then remove old data file. This reorganizes the LOB data there by releasing the unused space.
More Information
The following example shows you the unused space by using TSQL command sp_spaceused 'table_name' before and after you update the LOB column with smaller size of LOB data:
Before you update:
|
name |
rows |
reserved |
data |
index_size |
unused |
|
table_name |
1000 |
261072 KB |
261056 KB |
16 KB |
0 KB |
After you update:
|
name |
rows |
reserved |
data |
index_size |
unused |
|
table_name |
1000 |
261072 KB |
199672 KB |
16 KB |
61384 KB |
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
