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December 2010 Blog Posts

The internal storage of a DATETIMEOFFSET value

Today I went for investigating the internal storage of DATETIME2 datatype. What I found out was that for a datetime2 value with precision 0 (seconds only), SQL Server need 6 bytes to represent the value, but stores 7 bytes. This is because SQL Server add one byte that holds the precision for the datetime2 value. Start with this very simple repro declare    @now datetimeoffset(7) = '2010-12-15 21:04:03.6934231 +03:30'   select     cast(cast(@now as datetimeoffset(0)) as binary(9)),            cast(cast(@now as datetimeoffset(1)) as binary(9)),            cast(cast(@now as datetimeoffset(2)) as binary(9)),            cast(cast(@now as datetimeoffset(3)) as binary(10)),            cast(cast(@now as datetimeoffset(4)) as binary(10)),            cast(cast(@now as datetimeoffset(5)) as binary(11)),            cast(cast(@now as datetimeoffset(6)) as binary(11)),           ...

posted @ Wednesday, December 15, 2010 10:44 PM | Feedback (0) | Filed Under [ SQL Server 2008 Algorithms ]

The internal storage of a DATETIME2 value

Today I went for investigating the internal storage of DATETIME2 datatype. What I found out was that for a datetime2 value with precision 0 (seconds only), SQL Server need 6 bytes to represent the value, but stores 7 bytes. This is because SQL Server add one byte that holds the precision for the datetime2 value. Start with this very simple repro declare @now datetime2(7) = '2010-12-15 21:04:03.6934231'   select  cast(cast(@now as datetime2(0)) as binary(7)),         cast(cast(@now as datetime2(1)) as binary(7)),         cast(cast(@now as datetime2(2)) as binary(7)),         cast(cast(@now as datetime2(3)) as binary(8)),         cast(cast(@now as datetime2(4)) as binary(8)),         cast(cast(@now as datetime2(5)) as binary(9)),         cast(cast(@now as datetime2(6)) as binary(9)),         cast(cast(@now...

posted @ Wednesday, December 15, 2010 10:05 PM | Feedback (1) | Filed Under [ SQL Server 2008 Algorithms ]

A story from SQLvdb and Idera

A year or so back, I struggled with some consistency problems so I figured out I needed a way to "mount" backup files as a virtual database. At the time (SQL Server 2005 and SQL Server 2008) my choice fell on Idera's SQLvdb because it felt easy enough to use. I used it a few times and it worked great. Some time later we upgraded to SQL Server 2008R2 and I didn't use SQLvbd for a long time. Until yesterday... I was upset that suddenly SQLvbd took more than 2 hours to mount the backup file (if it succeeded at all). I...

posted @ Friday, December 10, 2010 9:33 AM | Feedback (0) | Filed Under [ Miscellaneous ]

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