SQL Server 2012 enhancements

1. By Abhishek Sur
Microsoft MVP, Client App Dev
Follow us at Twitter @abhi2434 & @sqlservergeeks

2. Why SQL Server 2012 ?
 Always On
 Contained Databases
 Column Store Indexes
 Visual Studio integration with Management Studio
 TSQL Enhancements
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4. The Concept
RowStore Page
Int Varchar Datetime float
• ColumnStore reduces
redundancy of data and
compression as the data type
remains same for the entire page.
• All data for a single column could
be retrieved from a non clustered
Columnstore Page index page.
Int Int Int Int float float float float
Limitation
• 1 Table can have one
columnstore index.
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6. Introducing SQL Server 2012 Transact-SQL
Improvements
• Query Pagination
• OVER Clause Windowing
• Sequences
• Metadata Discovery
• Enhanced Function Library
• General T-SQL-Related Enhancements

7. Query Pagination
• Common application requirement to retrieve rows
− For a given page
− For a given page length
− Our Options ???
− Retrieve all and filter in application end
− Retrieve data using Row_NUMBER function
− Any other options ?
− Denali gives better option for pagination

8. OVER Clause Windowing
• Some existing queries do not optimize well
• Example: Details of orders and days since previous order of each product
-- Traditional approach
SELECT rs.ProductKey,rs.OrderDateKey,rs.SalesOrderNumber,
rs.OrderDateKey- (SELECT TOP 1 prev.OrderDateKey
FROM dbo.FactResellerSales AS prev
WHERE rs.ProductKey=prev.ProductKey
AND prev.OrderDateKey<=rs.OrderDateKey
AND prev.SalesOrderNumber<rs.SalesOrderNumber
ORDER BY prev.OrderDateKey DESC,
prev.SalesOrderNumber DESC)
AS DaysSincePrevOrder
FROM dbo.FactResellerSales AS rs
ORDER BY rs.ProductKey,rs.OrderDateKey,rs.SalesOrderNumber;

9. OVER Clause Windowing
• Some existing queries do not optimize well
• Example: Details of orders and days since previous order of each product
-- Windowed approach
SELECT ProductKey,OrderDateKey,SalesOrderNumber,
OrderDateKey-LAG(OrderDateKey)
OVER (PARTITION BY ProductKey
ORDER BY OrderDateKey,SalesOrderNumber)
AS DaysSincePrevOrder
FROM dbo.FactResellerSales AS rs
ORDER BY ProductKey,OrderDateKey,SalesOrderNumber;

10. OVER Clause Windowing
• Some existing queries do not optimize well
• Example: Details of orders and days since previous order of each product

11. Sequences
• User-defined object
• Not tied to any particular table
• Not restricted to being used in a single table
• Eases migration from other database engines
• Does not support Transaction

12. Metadata Discovery
• Applications need to determine metadata associated with code batches or
stored procedures
• New functionality provided as both system stored procedures and via DMVs
− DMVs make the metadata easy to consume in a relational query
− Additional DMV option for passing an object ID (helpful for stored procedures or triggers)
System Stored Procedure Equivalent DMV
sp_describe_first_result_set sys.dm_exec_describe_first_result_set
sys.dm_exec_describe_first_result_set_for_object
• EXECUTE supports a WITH RESULT SETS clause

13. Enhanced Function Library
• New functions added
Conversion Date and Time Logical and String Analytic
PARSE DATEFROMPARTS CHOOSE CUME_DIST
TRY_PARSE TIMEFROMPARTS IIF PERCENTILE_DIST
TRY_CONVERT DATETIMEFROMPARTS CONCAT PERCENTILE_CONT
DATETIME2FROMPARTS FORMAT PERCENT_RANK
SMALLDATETIMEFROMPARTS FIRST_VALUE
DATETIMEOFFSETFROMPARTS LAST_VALUE
EOMONTH LEAD
LAG
• LOG function now supports an optional base

14. General T-SQL-Related Enhancements
• THROW statement
− Can throw user-errors
− Can rethrow any errors in a CATCH block (including system errors)
• Extended Events supports many new events
− Mostly relating to memory page allocation

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