sql server

1. SQL SERVER
Day 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. 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. 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. 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. Data Page

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. ORDER BY CLAUSE
• ORDER BY order_by_expression [ ASC |
DESC ] [ ,...n ]

9. JOINING OF TABLES
• INNER JOIN
• LEFT OUTER JOIN
• RIGHT OUTER JOIN
• FULL OUTER JOIN
• CROSS APPLY
• OUTER APPLY