Cardinality Estimates in SQL Server 2014 Thomas LaRock Head Geek SolarWinds

Why Are You Here? You are thinking about migrating/upgrading to SQL 2014 at some point

Why Are You Here? You are thinking about migrating/upgrading to SQL 2014 at some point You’ve been told to migrate to SQL 2014

Why Are You Here? You are thinking about migrating/upgrading to SQL 2014 at some point You’ve been told to migrate to SQL 2014 You want to understand more about specific changes to cardinality estimates

They let me keep the cape! A Little About Me… Thomas has over 15 years experience in roles including programmer, developer, analyst, and DBA. He is a frequent speaker, published author, and avid blogger on data related technologies. He enjoys working with data, probably too much to be healthy, really. They let me keep the cape!

A Little About Solarwinds… Network Management System Management IT Security Database Management solarwinds.com/products #Datachat

Agenda Why cardinality matters What’s new in SQL 2014 See the new CE in action Questions

Cardinality: Why It Matters

How most people see SQL Server 11/23/2018 How most people see SQL Server SQL © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

How most people see SQL Server 11/23/2018 How most people see SQL Server SQL QUERY © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

How most people see SQL Server 11/23/2018 How most people see SQL Server SQL QUERY DATA © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What’s inside the box? 11/23/2018 © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens When a Connection Is Made to SQL Server 11/23/2018 What Happens When a Connection Is Made to SQL Server Connection (Session ID) © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens When a Connection Is Made to SQL Server 11/23/2018 What Happens When a Connection Is Made to SQL Server Connection (Session ID) Request (Query sent) © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens When a Request Is Sent To SQL Server 11/23/2018 What Happens When a Request Is Sent To SQL Server Parse Syntax check; reserved keywords, column and table names © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens When a Request Is Sent To SQL Server 11/23/2018 What Happens When a Request Is Sent To SQL Server Parse Syntax check; reserved keywords, column and table names Bind Name reservation, type derivation, aggregates, grouping © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens When a Request Is Sent To SQL Server 11/23/2018 What Happens When a Request Is Sent To SQL Server Parse Syntax check; reserved keywords, column and table names Bind Name reservation, type derivation, aggregates, grouping Optimize Find “good enough” plan © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens When a Request Is Sent To SQL Server 11/23/2018 What Happens When a Request Is Sent To SQL Server Parse Syntax check; reserved keywords, column and table names Bind Name reservation, type derivation, aggregates, grouping Optimize Find “good enough” plan Execute Storage Engine © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens When a Request Is Sent To SQL Server 11/23/2018 What Happens When a Request Is Sent To SQL Server Logical Engine Parse Syntax check; reserved keywords, column and table names Bind Name reservation, type derivation, aggregates, grouping Optimize Find “good enough” plan Execute Storage Engine © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens When a Request Is Sent To SQL Server 11/23/2018 What Happens When a Request Is Sent To SQL Server Logical Engine Parse Syntax check; reserved keywords, column and table names Bind Name reservation, type derivation, aggregates, grouping Optimize Find “good enough” plan Execute Storage Engine © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens When a Connection Is Made to SQL Server 11/23/2018 What Happens When a Connection Is Made to SQL Server Connection (Session ID) Request (Query sent) © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens When a Connection Is Made to SQL Server 11/23/2018 What Happens When a Connection Is Made to SQL Server Connection (Session ID) Request (Query sent) Optimize (Optimization) © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens During Query Optimization in SQL Server 11/23/2018 What Happens During Query Optimization in SQL Server Primary goal: To find plan with “least cost” © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens During Query Optimization in SQL Server 11/23/2018 What Happens During Query Optimization in SQL Server Primary goal: To find plan with “least cost” Will stop when “good enough” plan is found © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens During Query Optimization in SQL Server 11/23/2018 What Happens During Query Optimization in SQL Server Primary goal: To find plan with “least cost” Will stop when “good enough” plan is found Uses statistics(!) to estimate rows needed for operators in the execution plan © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens During Query Optimization in SQL Server 11/23/2018 What Happens During Query Optimization in SQL Server Primary goal: To find plan with “least cost” Will stop when “good enough” plan is found Uses statistics(!) to estimate rows needed for operators in the execution plan The cost is an abstraction, no correlation to performance (ie., CPU ticks) © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What Happens During Query Optimization in SQL Server 11/23/2018 What Happens During Query Optimization in SQL Server Primary goal: To find plan with “least cost” Will stop when “good enough” plan is found Uses statistics(!) to estimate rows needed for operators in the execution plan The cost is an abstraction, no correlation to performance (ie., CPU ticks) Cost-based estimator; wants to find plan with lowest cost; will stop when “good enough” plan is found; uses statistics/histograms in order to estimate rows needed from tables/indexes to satisfy a query The primary goal for the Query Optimizer (QO) is to take the query tree that was produced after the Binding phase and to use that to find a “good enough” plan. Why do we say “good enough”? Because there could be thousands or millions of possible plan options and we don’t want SQL Server spending more time than necessary. Thus the concept of “good enough” comes about using a cost-based estimation process. The cost-based estimates are an abstraction; they don’t relate to anything except other estimates. In other words, they have no unit of value. You can’t say that a plan with lower cost will consume less CPU than another, for example. © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Query Optimization Model 11/23/2018 Query Optimization Model Contents are a mystery © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Query Optimization Model 11/23/2018 Query Optimization Model Contents are a mystery (except to Conor and his team) © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Query Optimization Model 11/23/2018 Query Optimization Model Contents are a mystery (except to Conor and his team) You don’t need the details © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Query Optimization Model 11/23/2018 Query Optimization Model Contents are a mystery (except to Conor and his team) You don’t need the details (no, you don’t) © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Query Optimization Model 11/23/2018 Query Optimization Model Contents are a mystery (except to Conor and his team) You don’t need the details (no, you don’t) You need the bigger picture © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

11/23/2018 The bigger picture Does plan already exist? In not, continue to next step. © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

11/23/2018 The bigger picture Does plan already exist? In not, continue to next step. Is this a trivial plan? If not, continue. © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

11/23/2018 The bigger picture Does plan already exist? In not, continue to next step. Is this a trivial plan? If not, continue. Apply simplification. © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

11/23/2018 The bigger picture Does plan already exist? In not, continue to next step. Is this a trivial plan? If not, continue. Apply simplification. Is this plan cheap enough? If not, continue. © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

11/23/2018 The bigger picture Does plan already exist? In not, continue to next step. Is this a trivial plan? If not, continue. Apply simplification. Is this plan cheap enough? If not, continue. Start cost-based optimization © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

11/23/2018 The bigger picture Does plan already exist? In not, continue to next step. Is this a trivial plan? If not, continue. Apply simplification. Is this plan cheap enough? If not, continue. Start cost-based optimization © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Cost-based optimization 11/23/2018 Cost-based optimization Explore basic rules © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Cost-based optimization 11/23/2018 Cost-based optimization Explore basic rules Does plan have a cost less than 0.2? © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Cost-based optimization 11/23/2018 Cost-based optimization Explore basic rules Does plan have a cost less than 0.2? Explore more rules, alternate join ordering. If the best plan is less than 1.0, use that plan. If not, but MAXDOP is > 0 and this is an SMP system and the min cost > cost for parallelism, then use a parallel plan. Compare the cost of parallel plan to best serial plan and pass the cheaper of the plans along. © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Cost-based optimization 11/23/2018 Cost-based optimization Explore basic rules Does plan have a cost less than 0.2? Explore more rules, alternate join ordering. If the best plan is less than 1.0, use that plan. If not, but MAXDOP is > 0 and this is an SMP system and the min cost > cost for parallelism, then use a parallel plan. Compare the cost of parallel plan to best serial plan and pass the cheaper of the plans along. Opt for the cheapest plan after a limited number of explorations © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Why This Matters Query optimizer contains the Cardinality Estimator (CE)

Why This Matters Query optimizer contains the Cardinality Estimator (CE) The CE is dependent upon statistics being current and accurate

Why This Matters Query optimizer contains the Cardinality Estimator (CE) The CE is dependent upon statistics being current and accurate If stats are missing, incorrect, or invalid then you are likely to get a sub-optimal plan

What’s inside the box? 11/23/2018 © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

The CE is the DNA for your queries! DNA is what makes you, you DNA not easily seen or understood CE is similar to DNA Tiny but BIG role Neither DNA nor CE are trivial pieces of code

What’s New In SQL Server 2014

The CE has been unchanged since 7.0! There have been slight enhancements over the years Hotfixes, patches, trace flags

The CE has been unchanged since 7.0! There have been slight enhancements over the years Hotfixes, patches, trace flags Goal for SQL2014 was not to avoid regression

The CE has been unchanged since 7.0! There have been slight enhancements over the years Hotfixes, patches, trace flags Goal for SQL2014 was not to avoid regression It is a new CE Will work better for most queries May not work well for some Testing is vital!

Legacy CE assumptions Uniformity Independence Containment Inclusion Prior to SQL Server 2014 the CE worked on a set of assumptions: Uniformity – That the data within the logical set was uniformly distributed (in the absence of statistical information). Independence – That the attributes in the entities are independent from each other. In other words, column1 is in no way related to column2. Containment – That two attributes which “might be the same” are treated as the same. In other words, when you join two tables an assumption is made that the distinct values from one table exist in the other. Inclusion – That when an attribute is compared to a constant there is always a match.

Legacy CE assumptions Uniformity Independence Containment Inclusion Prior to SQL Server 2014 the CE worked on a set of assumptions: Uniformity – That the data within the logical set was uniformly distributed (in the absence of statistical information). Independence – That the attributes in the entities are independent from each other. In other words, column1 is in no way related to column2. Containment – That two attributes which “might be the same” are treated as the same. In other words, when you join two tables an assumption is made that the distinct values from one table exist in the other. Inclusion – That when an attribute is compared to a constant there is always a match.

Legacy CE assumptions Uniformity Independence Containment Inclusion Prior to SQL Server 2014 the CE worked on a set of assumptions: Uniformity – That the data within the logical set was uniformly distributed (in the absence of statistical information). Independence – That the attributes in the entities are independent from each other. In other words, column1 is in no way related to column2. Containment – That two attributes which “might be the same” are treated as the same. In other words, when you join two tables an assumption is made that the distinct values from one table exist in the other. Inclusion – That when an attribute is compared to a constant there is always a match.

Legacy CE assumptions Uniformity Independence Containment Inclusion Prior to SQL Server 2014 the CE worked on a set of assumptions: Uniformity – That the data within the logical set was uniformly distributed (in the absence of statistical information). Independence – That the attributes in the entities are independent from each other. In other words, column1 is in no way related to column2. Containment – That two attributes which “might be the same” are treated as the same. In other words, when you join two tables an assumption is made that the distinct values from one table exist in the other. Inclusion – That when an attribute is compared to a constant there is always a match.

See the New CE in Action

Likely common scenarios 11/23/2018 Likely common scenarios ASC/DESC Key Estimates Multiple Column Dependency Join Estimates © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Likely common scenarios 11/23/2018 Likely common scenarios ASC/DESC Key Estimates Multiple Column Dependency Join Estimates © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Likely common scenarios 11/23/2018 Likely common scenarios ASC/DESC Key Estimates Multiple Column Dependency Join Estimates © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

New CE Changes That Require Action 11/23/2018 New CE Changes That Require Action If there are no changes to estimates or the query execution plan… © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

New CE Changes That Require Action 11/23/2018 New CE Changes That Require Action …but you are seeing degraded performance If there are no changes to estimates or the query execution plan… © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

New CE Changes That Require Action 11/23/2018 New CE Changes That Require Action …it’s not related to the new CE, but general performance tuning may be required …but you are seeing degraded performance If there are no changes to estimates or the query execution plan… © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

New CE Changes That Require Action 11/23/2018 New CE Changes That Require Action No changes to estimates but the query execution plan changed… © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

New CE Changes That Require Action 11/23/2018 New CE Changes That Require Action …and you are seeing degraded performance No changes to estimates but the query execution plan changed… © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

New CE Changes That Require Action 11/23/2018 New CE Changes That Require Action …unlikely to be related to the new CE, but tuning may be required …and you are seeing degraded performance No changes to estimates but the query execution plan changed… © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

New CE Changes That Require Action 11/23/2018 New CE Changes That Require Action If there are changes to the estimates regardless of the query execution plan shape… © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

New CE Changes That Require Action 11/23/2018 New CE Changes That Require Action …and you are seeing degraded performance If there are changes to the estimates regardless of the query execution plan shape… © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

New CE Changes That Require Action 11/23/2018 New CE Changes That Require Action …action may be necessary if degradation exceeds workload performance SLAs …and you are seeing degraded performance If there are changes to the estimates regardless of the query execution plan shape… © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Tips & Tricks

Tips and Tricks Auto Create/Update stats 11/23/2018 © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Tips and Tricks Auto Create/Update stats Database compatibility mode 11/23/2018 Tips and Tricks Auto Create/Update stats Database compatibility mode © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Tips and Tricks Auto Create/Update stats Database compatibility mode 11/23/2018 Tips and Tricks Auto Create/Update stats Database compatibility mode Query trace flags © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Tips and Tricks Auto Create/Update stats Database compatibility mode 11/23/2018 Tips and Tricks Auto Create/Update stats Database compatibility mode Query trace flags XML showplan, xEvents © 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Agenda Why cardinality matters What’s new in SQL 2014 See the new CE in action Questions

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Additional info http://tinyurl.com/joe-sack-cardinality http://tinyurl.com/sql-2014-new-CE http://tinyurl.com/sql-2014-new-CE-p2 http://tinyurl.com/CE-deep-dive-PWhite http://tinyurl.com/MSDN-CE-2014