1. SQL Server 2016 Execution Plan Analysis Liviu Ieran
12/2/2018 4:43 AM
SQL Server 2016 Execution Plan Analysis Liviu Ieran
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

2. Objectives Short Introduction to Execution Plans Most Encountered Operators Useful Information in a Plan Patterns to look out for

3. Short Introduction to Execution Plans
12/2/2018 4:43 AM
Short Introduction to Execution Plans
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

4. What is an Execution Plan? What is it good for?

5. Graphical Showplan Flow
12/2/2018 4:43 AM
Graphical Showplan Flow
Outer Table 5 3 1 2
Inner table 4 6
Resultset 1 and 2 are joined using a nested loops join, creating resultset 3
Resultset 3 and 4 are joined using a hash match join, creating resultset 5
Resultset 5 and 6 are joined using a nested loops join, creating a resultset for the Select clause
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

6. How to capture an execution plan
XEvents
SQL Server Management Studio (Query Menu)
sys.dm_exec_cached_plans
SQL Profiler

7. Most Encountered Operators
12/2/2018 4:43 AM
Most Encountered Operators
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

8. Operators – Physical Joins
12/2/2018 4:43 AM
Operators – Physical Joins
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

9. Nested Loops Join 12/2/2018 4:43 AM
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

10. 12/2/2018 4:43 AM
Merge Join
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

11. 12/2/2018 4:43 AM
Hash Join
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

12. Seek Operators Index Seek Clustered Index Seek
Range Scans appear as either clustered or non- clustered index seeks with a RANGE predicate
12/2/2018 4:43 AM
Seek Operators
Index Seek
Clustered Index Seek
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

13. Scan Operators Table Scan Clustered Index Scan Index Scan
12/2/2018 4:43 AM
Scan Operators
Table Scan
Clustered Index Scan
Index Scan
Columnstore Index Scan
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

14. Notable Operators Table Spool Index Spool Sort Stream Aggregation
Hash Match (Aggregation)
References
For more information, see: Showplan Logical and Physical Operators Reference -
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

15. Demonstration: Join Algorithms
12/2/2018 4:43 AM
Demonstration: Join Algorithms
SELECT sod.OrderQty, od.EventDetails FROM Sales.OrderTracking od
INNER JOIN Sales.SalesOrderDetail sod ON od.SalesOrderID = sod.SalesOrderID
SELECT TOP 1000 sod.OrderQty, od.EventDetails FROM Sales.OrderTracking od
SELECT TOP 10 sod.OrderQty, od.EventDetails FROM Sales.OrderTracking od
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

16. Useful Information in a Plan
12/2/2018 4:43 AM
Useful Information in a Plan
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

17. Contents of a Query Plan
12/2/2018 4:43 AM
Contents of a Query Plan
How data is accessed and joined
Sequence of operations
Use of sorts
Estimated vs. Actual row counts and iterations
How data is aggregated
Use of parallelism
Query execution warnings
….and many more
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

18. Demonstration: Graphical Query Plans
12/2/2018 4:43 AM
Demonstration: Graphical Query Plans
--demo 2a
SET CONCAT_NULL_YIELDS_NULL OFF
SET STATISTICS TIME ON
SELECT p.FirstName + ' ' + p.MiddleName + ' ' + p.LastName as FullName,
a.City,
a.AddressLine1 as Adress,
at.Name as AdressType
FROM Person.Person p
INNER JOIN Person.BusinessEntityAddress bea ON p.BusinessEntityID = bea.BusinessEntityID
INNER JOIN Person.Address a ON bea.AddressID = a.AddressID
INNER JOIN Person.AddressType at ON at.AddressTypeID = bea.AddressTypeID
--demo 2b
EXEC uspGetEmployeeManagers 30 GO
EXEC uspGetEmployeeManagers 40
--dbcc freeproccache
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

19. Patterns to look out for
12/2/2018 4:43 AM
Patterns to look out for
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

20. Patterns to look out for
12/2/2018 4:43 AM
Patterns to look out for
Very thick arrows <–> large amount of data
Table Scans (do I have a where clause?)
Huge difference between estimated and actual rows
High numbers of RID or Key lookups
Query execution warnings:
Spills to tempdb
Implicit conversions
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

21. Demonstration: Look for patterns
12/2/2018 4:43 AM
Demonstration: Look for patterns
--demo 3a
USE [AdventureWorks2016CTP3] GO
DROP TABLE IF EXISTS [dbo].[SalesOrderHeader_SQLSA]
DROP TABLE IF EXISTS [dbo].[SalesOrderdetail_SQLSA]
DROP TABLE IF EXISTS [dbo].[customer_SQLSA]
SELECT * INTO SalesOrderHeader_SQLSA
FROM Sales.SalesOrderHeader
SELECT * INTO SalesOrderdetail_SQLSA
FROM Sales.SalesOrderDetail
SELECT * INTO Customer_SQLSA
FROM Sales.Customer
SET STATISTICS TIME ON
SET STATISTICS IO ON
SELECT c.CustomerID,
so.OrderDate, so.ShipDate,
sod.ProductID, sod.OrderQty, sod.UnitPrice, sod.UnitPriceDiscount
FROM dbo.Customer_SQLSA c
JOIN dbo.SalesOrderHeader_SQLSA so ON c.CustomerID=so.CustomerID
JOIN dbo.SalesOrderdetail_SQLSA sod ON so.SalesOrderID= sod.SalesOrderID
WHERE ShipDate between '07/01/2012' AND '07/31/2012'
USE [master]
ALTER DATABASE [AdventureWorks2016CTP3] SET AUTO_CREATE_STATISTICS ON WITH NO_WAIT
ALTER DATABASE [AdventureWorks2016CTP3] SET AUTO_CREATE_STATISTICS OFF WITH NO_WAIT
FROM Sales.Customer c
JOIN Sales.SalesOrderHeader so ON c.CustomerID=so.CustomerID
JOIN Sales.SalesOrderdetail sod ON so.SalesOrderID= sod.SalesOrderID
WHERE ShipDate between '07/01/2012' AND '07/31/2012‘
--demo 3b
DROP TABLE IF EXISTS [dbo].[Person_SQLSA]
SELECT * INTO Person_SQLSA
FROM Person.Person
ALTER TABLE [dbo].[Person_SQLSA] ALTER COLUMN FirstName varchar (50) ;
CREATE NONCLUSTERED INDEX [IX_Person_Firstname] ON [dbo].[Person_SQLSA] (
[FirstName] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
select * from dbo.Person_SQLSA
WHERE FirstName = N'Clay'
WHERE FirstName = 'Clay‘
--demo 3c
SELECT * FROM Sales.OrderTracking ot
INNER JOIN Sales.SalesOrderDetail sod ON ot.SalesOrderID = sod.SalesOrderID
WHERE EventDetails LIKE 'ORDER%'
Order by ot.EventDetails
CREATE STATISTICS [TempStat] ON [Sales].[OrderTracking]([EventDetails])
dbcc freeproccache
DROP STATISTICS [Sales].[OrderTracking].[TempStat]
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

22. A few short tips Keep stats up to date (fullscan)
12/2/2018 4:43 AM
A few short tips
Keep stats up to date (fullscan)
Are my where clauses indexed?
Are my join conditions indexed?
OldCE vs NewCE (since SQL 2014)
TF4199 (pre SQL 2016, comp level 130)
Matching data types
Defragment indexes
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

23. 12/2/2018 4:43 AM
Questions?
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

24. 12/2/2018 4:43 AM
Note: This should be the final slide for each presentation
© 2014 Microsoft Corporation. All rights reserved. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.