Sql server 2

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sql server

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Sql server 2

  1. 1. SQL SERVER Day 2
  2. 2. Natural Order• When you do a SELECT FROM the table, the rows will ALWAYS appear in the same order of insertion• It’s the “natural” chronologically-entered order of the rows
  3. 3. Natural Order• Table data is stored as a collection of 8-KB (8192-byte) pages.• 8060 bytes for the data on each page.• A row of data can not span multiple pages.
  4. 4. Why Optimizer chooses NCI• a nonclustered index will have less data in its pages than a clustered one• The size of a nonclustered index will be either equal to or less than the size of a clustered index… it will never be bigger…
  5. 5. Pages and Extents• The fundamental unit of data storage in SQL Server is the page.• Size of a page is 8 KB (96-byte header )• Header store system information about the page:• Page Number• Page Type• Free pace on the page• Allocation unit ID
  6. 6. Data Page
  7. 7. Extents• Page type: Data, Index, LOB, ROW_OVERFLOW_DATA etc.• Extents are the basic unit in which space is managed.• Extents are a collection of eight physically contiguous pages
  8. 8. ORDER BY CLAUSE• ORDER BY order_by_expression [ ASC | DESC ] [ ,...n ]
  9. 9. JOINING OF TABLES• INNER JOIN• LEFT OUTER JOIN• RIGHT OUTER JOIN• FULL OUTER JOIN• CROSS APPLY• OUTER APPLY

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