Jon Gurgul's Blog

Tag: Storage

  • SQL Server Row Internals

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    Jon Gurgul
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    Row Storage A Row is stored on a Page which is 8192 Bytes, and this is broken down in two key areas when considering physical storage. Firstly on all pages there is a 96 Byte Header. In addition to this we also need to store the Row structure as well as its location in the…

  • SQL Server Max Row Size 8060 Part 2

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    Jon Gurgul
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    In my previous post on row maximum length I showed that the largest row size that could be stored on page was 8053 byte. So to recap a table with 2 fixed length columns CHAR(8000) & CHAR(53) the internal storage would look as below, with an unused space of 34 bytes. Page Header 96 bytes…

  • SQL Server Max Row Size 8060

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    Jon Gurgul
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    When asked the size of the largest row that could be placed on to a single SQL Server data page the answer that most give is 8060 bytes. If you try to create a fixed length table with columns that total this length however it throws an error. Please create a database to run this test and…

  • Delta and Cumulative IO Stats

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    Jon Gurgul
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    Checking IO statistics has always been one of the most important metrics for any DBA. It is no surprise that most people I know will have some version of the following two scripts that use the dmv sys.dm_io_virtual_file_stats (Transact-SQL). The dmv itself is a cumulative view of your IO, therefore in order to get a particular…