SQL Server 2012 Database Server Programmability

By Abhishek Sur Microsoft MVP, Client App DevFollow us at Twitter @abhi2434 & @sqlservergeeks

Why SQL Server 2012 ? Always On Contained DatabasesColumn Store IndexesVisual Studio integration with Management StudioTSQL Enhancements

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ColumnStore Index…

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The Concept

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Int Varchar Datetime float

float float float floatInt Int Int Int

RowStore Page

Columnstore Page

• 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 index page.

Limitation• 1 Table can have one

columnstore index.

Introducing SQL Server 2012 Transact-SQL Improvements

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Introducing SQL Server 2012 Transact-SQL Improvements• Query Pagination• OVER Clause Windowing• Sequences• Metadata Discovery• Enhanced Function Library• General T-SQL-Related Enhancements

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

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.OrderDateKeyFROM dbo.FactResellerSales AS prevWHERE rs.ProductKey=prev.ProductKeyAND prev.OrderDateKey<=rs.OrderDateKeyAND prev.SalesOrderNumber<rs.SalesOrderNumberORDER BY prev.OrderDateKey DESC,prev.SalesOrderNumber DESC)AS DaysSincePrevOrderFROM dbo.FactResellerSales AS rsORDER BY rs.ProductKey,rs.OrderDateKey,rs.SalesOrderNumber;

-- Traditional approach

SELECT rs.ProductKey,rs.OrderDateKey,rs.SalesOrderNumber,rs.OrderDateKey- (SELECT TOP 1 prev.OrderDateKeyFROM dbo.FactResellerSales AS prevWHERE rs.ProductKey=prev.ProductKeyAND prev.OrderDateKey<=rs.OrderDateKeyAND prev.SalesOrderNumber<rs.SalesOrderNumberORDER BY prev.OrderDateKey DESC,prev.SalesOrderNumber DESC)AS DaysSincePrevOrderFROM dbo.FactResellerSales AS rsORDER BY rs.ProductKey,rs.OrderDateKey,rs.SalesOrderNumber;

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 ProductKeyORDER BY OrderDateKey,SalesOrderNumber)AS DaysSincePrevOrderFROM dbo.FactResellerSales AS rsORDER BY ProductKey,OrderDateKey,SalesOrderNumber;

-- Windowed approach

SELECT ProductKey,OrderDateKey,SalesOrderNumber,OrderDateKey-LAG(OrderDateKey)OVER (PARTITION BY ProductKeyORDER BY OrderDateKey,SalesOrderNumber)AS DaysSincePrevOrderFROM dbo.FactResellerSales AS rsORDER BY ProductKey,OrderDateKey,SalesOrderNumber;

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

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

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)

• EXECUTE supports a WITH RESULT SETS clause

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

Enhanced Function Library• New functions added

• LOG function now supports an optional base

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

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

Thank You !

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