Database Snapshot

Hi Has anyone used Database Snapshots? From what I understand these became available in SQL 2005 Enterprise Edition, unfortunately I currently only have Standard so can't have a 'play'. Any feedback on these would be gratefully received, on how they have been useful or not.

Many thanks

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asked Jun 06, 2011 at 06:39 AM in Default

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also available in 'Developer' flavour.....

Jun 06, 2011 at 06:40 AM Kev Riley ♦♦

Enterprise is available for a 6m trial from the installer CD...

Jun 06, 2011 at 06:44 AM Fatherjack ♦♦
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Some of my typical uses for Database Snapshots include:

  • Supporting small data changes in Production by providing a hot restore option. (No need to take a database backup when a Snapshot can be used to store just the delta of changed data.)

  • In conjunction with Database Mirroring, can be used to provide read access to the Mirrored database data.(Useful in typical query/reporting offloading scenarios but not as flexible as a Replicated DB, which permits local optimisations such as workload specific indexes).

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answered Jun 07, 2011 at 01:22 AM

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John Sansom
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I use database snapshots in development, when testing ideas or performing restructuring-by-brainstorming. I start off making a snapshot, go wild and crazy in a development database, and then use the snapshot to go back to the original state when I'm finished playing/testing ideas. That way, I don't need to take a copy of a database just to go bananas with it.

A database snapshot is initially an empty sparse file. It's an allocation of disk space, but the file itself is empty. As the original datafile changes, Windows will fill the sparse-file with the original data. So if you create a snapshot, and then change or delete a datapage, Windows will first write the original datapage to the sparse-file, and then change/delete the datapage.

The way it's implemented, creating a database snapshot is very, very quick, as Windows won't really copy data, it will just create some meta-data about the data. Restoring/reverting from a snapshot is also a quick process (if only little data has been changes since creating the snapshot), since only the changed pages are restored.

Some reading on database snapshots in SQL Server 2005: http://msdn.microsoft.com/en-us/library/ms175158(v=SQL.90).aspx

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answered Jun 07, 2011 at 01:37 AM

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Magnus Ahlkvist
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asked: Jun 06, 2011 at 06:39 AM

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