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By: Armando Prato | Read Comments (1) | Print Armando has over 24 years of industry experience and has been working with SQL Server since version 6.5. Related Tips: More |
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Problem
In one of your recent tips, you mention that SQL Server keeps a history of all backups and restores that have been made in the system. Our organization performs backups and restores frequently and I've noticed our msdb database is very large because of this. How can I purge some of this data and free some database space?
Solution
As mentioned in this tip, SQL Server keeps records of backup and restore activity in system tables within the msdb database. Without regular maintenance, these system tables can grow to very large sizes leading to a large overall size for the msdb database.
These msdb tables include:
Luckily, Microsoft provides two system stored procedures that you can use to trim the size of the msdb database tables that hold this data. The first procedure deletes all backup and restore history older than a provided date. The 2nd procedure allows you to delete all backup and restore history for a specific database. Let's look at these in more detail.
On my system, looking at msdb tables backupset and restorehistory, I see the following database backups and restores that have been performed:
The first procedure that can be used is sp_delete_backuphistory. This system stored procedure takes a single parameter - a cutoff date. Any data older than the supplied date is purged from the msdb tables listed earlier in this tip. In the following example, I'll purge all data older than 4/2/2009.
-- delete all backup/restore history prior to a specified date use msdb go exec sp_delete_backuphistory '2009-04-02' go |
Examining the tables again, we see that all backup history prior to 4/2/2009 has been purged with restorehistory tied to these entries being purged as well:
The 2nd system stored procedure allows you to delete historical backup data for a specific database and is called sp_delete_database_backuphistory. Unfortunately, this procedure does not offer the finer option of choosing a cutoff date; It's all or nothing. In the next example, I'll delete all backup history for a specific database.
-- delete all backup history for a specific database use msdb go exec sp_delete_database_backuphistory 'test1' go |
As you can see, only history for the specified database has been purged:
Next Steps
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| Friday, April 10, 2009 - 11:35:47 AM - brian@escription.com | Read The Tip | ||
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Yep my company takes a full backup of SQL Server nightly and transaction log backups every 15 minutes or basically 96 backups a day. Furthermore we can only keep 1 or 2 days worth on the main server and we copy them off to an off-site location, so purging that database is critical. Here are two lesser known pitfall about the purge backup history command: 1. There is a missing index in msdb so create it yourself
2. The stored procedure that deletes the backup history uses cursors in an inappropriate way, you could re-create the procedure to not use the cursors. If you purge routinely (nightly) it isn't really necessary, but it does show that MSFT does not follow their own advice, and worse yet I have had a tech say NEVER use a cursor, and when I show him what I want to do he says use the SP for each database, guess what that uses a cursor. Good luck. |
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