The Resource Governor is an important feature in SQL Server that enables you to effectively manage SQL Server workload and resources by creating limits on resource consumption by incoming requests. This ensures the optimal performance of the SQL Server in multi-load environments and serves an essential role in Administering Microsoft Azure SQL solutions.
Introduction to Resource Governor
Resource Governor essentially controls the allocation of CPU, physical IO, and memory resources to user-requests or processes. By categorizing incoming connections and distributing the resources that you specify to each workload group, it ensures that high-priority workloads aren’t compromised by low-priority ones. This is specifically crucial in a consolidated environment where multiple applications are competing for resources.
Configuring the Resource Governor
Configuring the Resource Governor involves a few steps:
- Classifier Function: The classifier function is a user-defined function that you write yourself to classify sessions into specific workload groups. Let’s take an example:
CREATE FUNCTION dbo.Classifier_Function()
RETURNS SYSNAME
WITH SCHEMABINDING
AS
BEGIN
RETURN
CASE
WHEN (SUSER_NAME() = 'User1') THEN 'GroupA'
ELSE 'default'
END
END;
This classifier function routes the session from User1 to the workload group `GroupA` and all other users to the default group.
- Resource Pools: Define the resource pools that define the boundaries of the resources for a workload.
CREATE RESOURCE POOL PoolA
WITH
( MAX_CPU_PERCENT = 50,
MAX_MEMORY_PERCENT = 50,
MAX_IOPS_PER_VOLUME = 5000
);
CREATE RESOURCE POOL PoolB
WITH
( MAX_CPU_PERCENT = 25,
MAX_MEMORY_PERCENT = 25,
MAX_IOPS_PER_VOLUME = 2500
);
Here, two resource pools are created, `PoolA` and `PoolB` with different CPU, memory and IO limits.
- Workload Groups: Assign the workload groups to the resource pools.
CREATE WORKLOAD GROUP GroupA
USING PoolA;
CREATE WORKLOAD GROUP GroupB
USING PoolB;
Here, the workload group `GroupA` is using the resources from `PoolA` and `GroupB` is using the resources from `PoolB`.
- Register Classifier Function: Register your classifier function with the Resource Governor.
ALTER RESOURCE GOVERNOR
WITH (CLASSIFIER_FUNCTION = dbo.Classifier_Function);
- Enable Resource Governor:
ALTER RESOURCE GOVERNOR RECONFIGURE;
Verifying and Monitoring Resource Governor
After you have configured the Resource Governor, it is essential to verify and monitor its implementation to ensure it’s functioning as expected. This can be done using the Dynamic Management Views (DMVs) provided by the SQL Server, such as `sys.dm_resource_governor_resource_pools`, `sys.dm_resource_governor_workload_groups`, and `sys.dm_resource_governor_configuration`.
Configuring Resource Governor effectively improves the performance of your SQL Server by providing more control over the distribution of resources, and this feature is particularly beneficial in an Azure SQL environment where resources are often shared among multiple applications.
Practice Test
True/False: The Resource Governor can be used to manage CPU, physical I/O, and memory resources for SQL Server.
- True
- False
Answer: True
Explanation: Resource Governor is a feature in SQL Server that allows you to manage SQL Server workloads and resources by specifying limits on resource consumption by incoming requests.
In the Resource Governor, what is a workload group?
- A. A set of users
- B. A set of resources
- C. A set of requests
- D. None of the above
Answer: C. A set of requests
Explanation: In Resource Governor, a workload group is a set of similar requests grouped together. Each workload group is associated with a resource pool.
True/False: You cannot define your own resource pools in the SQL Server Resource Governor.
- True
- False
Answer: False
Explanation: In the SQL Server Resource Governor, you have the option to define your own resource pools apart from the default ones.
Which of the following actions can you NOT perform with Resource Governor?
- A. Limit CPU usage
- B. Allocate Memory
- C. Manage User Permissions
- D. Manage I/O
Answer: C. Manage User Permissions
Explanation: Resource Governor is used to manage SQL Server workloads and resources, not user permissions.
True/False: In SQL Server Resource Governor, you can assign a specific workload group to a specific resource pool.
- True
- False
Answer: True
Explanation: In SQL Server Resource Governor, you can indeed specify which resource pool a workload group should use, allowing you to further customize resource allocation.
What is the maximum number of workload groups you can have per resource pool in SQL Server Resource Governor?
- A. 1
- B. 10
- C. 32
- D. Unlimited
Answer: D. Unlimited
Explanation: SQL Server Resource Governor allows you to have an unlimited number of workload groups per resource pool.
True/False: Resource Governor allows you to limit the number of active requests in SQL Server.
- True
- False
Answer: False
Explanation: While Resource Governor allows you to manage resources, it does not allow you to limit the number of active requests.
Which version of SQL Server first introduced the Resource Governor?
- A. SQL Server 2005
- B. SQL Server 2008
- C. SQL Server 2012
- D. SQL Server 2016
Answer: B. SQL Server 2008
Explanation: The Resource Governor was introduced in SQL Server 2008 to manage SQL Server workloads and system resource consumption.
True/False: Using the Resource Governor, you can specify minimum and maximum CPU usage percentages for workloads.
- True
- False
Answer: True
Explanation: Resource Governor allows you to specify minimum and maximum CPU usage percentages for workload groups.
With respect to Resource Governor, what is a Classifier Function?
- A. A function to classify resources
- B. A function to classify workload groups
- C. A function to classify incoming requests
- D. None of the above
Answer: C. A function to classify incoming requests
Explanation: In Resource Governor, a Classifier Function is a user-defined function that categorizes incoming connections and assigns them to a specific workload group.
Interview Questions
What is the Resource Governor in Microsoft Azure SQL?
The Resource Governor is a feature in Microsoft Azure SQL that allows you to manage SQL Server workload and system resource consumption.
What is the primary benefit of configuring the Resource Governor for performance in Azure SQL?
The primary benefit is that it allows for the specification of limits on the amount of CPU, physical IO, and memory that incoming application requests can use, preventing system overloads and optimizing performance.
How many resource pools can be created in Resource Governor?
A maximum of 64 resource pools can be created in Resource Governor for each instance of SQL Server Database Engine.
What is a workload group in the context of Azure SQL’s Resource Governor?
A workload group serves as a container for session requests that have similar classification criteria. It contains specific settings that control how much resources a session using it can take from the resource pool.
What is a classifier function in the context of Azure SQL’s Resource Governor?
A classifier function is a user-defined function that maps incoming connections to workload groups. It’s used to categorize the incoming session requests based on characteristics like application name, user name, or client IP address, and route them to the corresponding workload group.
How can the Resource Governor be enabled in Azure SQL?
The Resource Governor can be enabled by either using SQL Server Management Studio, or by running the ALTER RESOURCE GOVERNOR RECONFIGURE statement in the Transact-SQL.
Is it possible to make changes to the Resource Governor settings once it is enabled?
Yes, changes can be made to the Resource Governor settings even after it’s enabled. However, the ALTER RESOURCE GOVERNOR RECONFIGURE statement needs to be executed for changes to take effect.
What is the purpose of the DEFAULT group in Resource Governor?
The DEFAULT group is a built-in workload group that handles all sessions that aren’t allocated to any other workload group by the classifier function.
What is the role of the MIN_CPU_PERCENT configuration option in Resource Governor?
The MIN_CPU_PERCENT configuration option in Resource Governor specifies the minimum amount of CPU resources that are guaranteed to the resource pool.
Can a session use more than the maximum resources specified for a resource pool in Resource Governor?
Yes, a session can use more than the maximum resources specified only if there are idle resources. It cannot exceed its maximum limit when the system is under load.
What happens to the running sessions when a Resource Governor configuration is changed in Azure SQL?
When a Resource Governor configuration change is made, active sessions continue to use the old configuration until their next recompilation or until they are ended. New sessions use the new configuration.
How can you check the current configuration of Resource Governor in Azure SQL?
The current configuration of the Resource Governor can be viewed by querying the sys.resource_governor_configuration dynamic management view.
Is it possible to use Resource Governor to manage resources for Azure SQL Database?
No, Resource Governor cannot be used to manage resources for Azure SQL Database as Resource Governor is only available in SQL Server and Azure SQL Managed Instance.
What is the effect of setting MAX_CPU_PERCENT to 0 in Resource Governor?
Setting MAX_CPU_PERCENT to 0 in Resource Governor means that the resource pool will not use CPU resources.
How can you disable Resource Governor in Azure SQL?
The Resource Governor can be disabled by setting is_disabled to 1 in sys.resource_governor_configuration and then running the ALTER RESOURCE GOVERNOR RECONFIGURE statement.
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