I have a SQL Server database of size 270GB. Almost 91% of the space is showing up as UNUSED in space report. I know unused space is space allocated to a particular object. App team did a purge operation on the DB but we couldn't really claim space with that.
I have checked index fragmentation on the table but they look good.. What else i need to be checking and what is that i should do to release that space. The DB is not going to use that space anytime in future.
As per my understanding DBCC SHRINKFILE releases only unallocated space. I've read about DBCC CLEANTABLE and DBCC SHRINK DATABASE but not sure if it's good enough to perform.
How to effectively release unused space from objects.
So to my understanding, you first need to shrink the files, then you can shrink the DB:
Using SQL Server Management Studio:
Shrink the files: r-click on DB, 'Tasks', 'Shrink', 'Files': Then pick a new file size value slightly larger than the 'Minimum is' value given in the dialog.
Shrink the database: r-click on DB, 'Tasks', 'Shrink', 'Database' (tick the 'Reorganize files checkbox)
With this, I was able to reduce the percentage of 'unused' space in the Disk report. There is still quite some left though (20%) .. I think 'reorganizing' some indices might help.
If there are only indexes in your database then you can drop your old filegroup after creating a new filegroup and moving all indexes into it.you can move the indexes using CREATE INDEX ... WITH DROP_EXISTING
Related
In SQL Server, in one of our databases, we have a big database table that's using over 1.2 TB of space. It has about 200 GB of actual data but over 1 TB of unused space.
This happened over 2 years as old time series data was deleted from this table daily and new data was inserted daily.
We do not expect for the table size to increase much going forward.
I am looking for the best way to reclaim unused space from this table without taking the database or table offline, and without causing too much CPU overhead.
I think for this you'll need to use DBCC Shrinkfile, possibly in several incremental steps.
First see if truncateonly has an acceptable effect - it depends on how the data is distributed within the file
DBCC SHRINKFILE (N'Tablename' , truncateonly)
If the file does not shrink sufficiently you can specify a target size to shrink to in MB eg
DBCC SHRINKFILE (N'Tablename' , 256000)
You can monitor the impact on performance while this executes and stop it if need be, resuming again as appropriate.
I have virtualbox with oracle database. So, I had 5 gb space left. I tried to import 2gb something dmp file, and it failed after disk became full. So, I tried to drop it by using "DROP USER ABC";
The username was dropped but the space was not recovered.
Please let me know I would be able recover this space?
Thank you.
Did you use the "CASCADE" option? If the user dropped without that option, then it didn't own any database objects and would not have recovered any space. There are other ways you could have lost the space, too, besides from the data itself: archived transaction logs, space for indexes (that don't store data in the dmp files), and the growth of the TEMP tablespace come immediately to mind.
Use the DBA_SEGMENTS view to establish which objects are actually taking up space in your database, which users own them, and which tablespaces they're located in:
https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/DBA_SEGMENTS.html
http://dba-oracle.com/t_dba_segments.htm
Also check your archivelog location, automatic diagnostic repository (ADR) for log and trace file growth, and see if you can reduce the size of your TEMP tablespace (if it seems to have grown).
I have created a table on SQL Server then inserted 135 million records in that table.
then I truncate it
then tried to re-insert the same 135 million records again.
but something went wrong and had to restart the computer
I got the recovery mode in my database.
then fixed.
the problem now is C drive has 10GB free only (210GB used) while before that I used to have 105GB free!
I checked folders but the sum of all sizes including hidden ones does not sum to 210GB
what happened and where did these GBs have gone?
The space is not automatically released by the database. In the case of tempdb, if you restart the sql service, tempdb will reinitialize to original size. But, not the case for other databases.
If you want to reclaim the space, there are two approaches:
Cleaner approch:
As suggested by Paul Randal, go for new filegroup for existing tables and then drop the old filegroup.Refer to his article
Create a new filegroup
Move all affected tables and indexes into the new filegroup using the CREATE INDEX … WITH (DROP_EXISTING = ON) ON syntax, to move the
tables and remove fragmentation from them at the same time
Drop the old filegroup that you were going to shrink anyway (or shrink it way down if its the primary filegroup)
Brute Force approach and redmediation
Here, you can use DBCC SHRINKFILE and reduce the size. Keep little more space in the database to avoid frequent autogrowth. Beware that, shrinking file will lead to index fragmentation and you have to rebuild indexes post the shrinking of files.
As Paul Randal recommends:
If you absolutely have no choice and have to run a data file shrink
operation, be aware that you’re going to cause index fragmentation and
you might need to take steps to remove it afterwards if it’s going to
cause performance problems. The only way to remove index fragmentation
without causing data file growth again is to use DBCC INDEXDEFRAG or
ALTER INDEX … REORGANIZE. These commands only require a single 8KB
page of extra space, instead of needing to build a whole new index in
the case of an index rebuild operation (which will likely cause the
file to grow).
I have 2 databases from which I have deleted rows in a specific table in order to decrease the size of the database.
After deleting, the size of DB.mdf does not change.
I also tried to rebuild the index and used cleantable, but to no effect!
ALTER INDEX ALL ON dbo.'Tablename' REBUILD
DBCC CLEANTABLE ('DBname', 'Tablename', 0)
Deleting rows in a database will not decrease the actual database file size.
You need to compact the database after row deletion.
Look for this
After running this, you'll want to rebuild indexes. Shrinking typically causes index fragmentation, and that could be a significant performance cost.
I would also recommend that after you shrink, you re-grow the files so that you have some free space. That way, when new rows come in, they don't trigger autogrowth. Autogrowth has a performance cost and is something you would like to avoid whenever possible.
You need to shrink the db. Right click db, Tasks->Shrink database
Even I faced the same issue, my db was 40MB after deleting some columns still its size was not getting changed..
I installed SQLManager then opened my db and used command 'vaccum' that cleaned my db and its size got reduced to 10MB.
I wrote this after being in the exact same scenario and needing to shrink the database. However, not wanting to use DBCC SHRINFKILE I used Paul Randals method of shrinking the database.
https://gist.github.com/tcartwright/ea60e0a38fac25c847e39bced10ecd04
I have an application that logs to a DB2 database. Each log is stored in a daily table, meaning that I have several tables, one per each day.
Since the application is running for quite some time, I dropped some of the older daily tables, but the disk space was not reclaimed.
I understand this is normal in DB2, so I goggled and found out that the following command can be used to reclaim space:
db2 alter tablespace <table space> reduce max
Since the tablespace that store the daily log tables is called USERSPACE1, I executed the following command successfully:
db2 alter tablespace userspace1 reduce max
Unfortunately the disk space used by DB2 instance is still the same...
I've read somewhere that the REORG command can be executed, but what I've seen it is used to reorganize tables. Since I dropped the tables, how can I use REORG?
Is there any other way to do this?
Thanks
Reduce the size of a tablespace is very complex. The extents (set of contiguous pages; unit of tablespace allocation) of the tables are not distributed sequentially for a same table. When you reorg a table, the rows will be organized in pages, and the new pages will be written normally at the end of the tablespace. Sometimes, the high watermark will be increased, and your tablespace will be bigger.
You need to reorg all tables from a tablespace in order to "defrag" all tables. Then, you have to perform a new reorg in order to use the previous space, because it should be an empty space in the tablespace.
However, there are many criteria that impacts the organization of the tables in a tablespace: New extents are created (new rows, rows overflow due to updates); compression could be activated after reorg.
What you can do is to assign few or just one table per tablespace; however, you will waste a lot of space (overhead, empty pages, etc.)
The command that you are using is an automatic way to do that, but it does not always work as desired: http://www-01.ibm.com/support/knowledgecenter/SSEPGG_10.5.0/com.ibm.db2.luw.admin.dbobj.doc/doc/c0055392.html
If you want to see the distribution of the tables in your tablespace, you can use db2dart. Then, you can have an idea of which table to reorg (move).
Sorry guys,
The command that I mentioned on the original post works after all, but the space was retrieved very slowly.
Thanks for the help