How is it possible to set the minimum amount of CPU for a database inside a pool in Azure?

Bruno Silva 5

Good afternoon,

For some time now, we have been experiencing issues regarding resources in a database pool. as a first solution we decided to increase the amount of vCore to improve processing, for a few days everything went well, but today a strange situation happened …

Even with resources available in the pool, at the peak moment of a db it considerably decreases the CPU % of another db... with that it ended up generating a slowdown in our entire system. User's image

In consultation with our database using the query

SELECT * FROM SYS.DM_USER_DB_RESOURCE_GOVERNANCE AS RG WHERE DATABASE_ID = DB_ID();

We have identified that the MIN_CPU is set to 0.

How can we perform an operation to change this MIN_CPU value?

How is it possible to set the minimum amount of CPU for a database inside a pool in Azure?

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I N 0 Reputation points

2024-03-19T03:34:14.98+00:00

Bruno, how did you resolve your problem?

And could you give a little bit more context? When you said 'it considerably decreases the CPU % of another db...' does it mean that the second database performance was suffering or both of them? Was the second database active at the same time and competing for computing resources with the first DB?
Oury Ba-MSFT 19,886 Reputation points Microsoft Employee

2024-04-05T17:31:50.9833333+00:00

I N

Please check this https://learn.microsoft.com/en-us/azure/azure-sql/database/resource-limits-vcore-elastic-pools?view=azuresql#database-properties-for-pooled-databases
I N 0 Reputation points

2024-04-10T06:13:00.15+00:00

@Oury Ba-MSFT Thanks for providing the link, I have seen this before.
What I am more interested - if default setting of 0 for min value causes all databases to throttle, as it was indicated in Bruno's message.
Oury Ba-MSFT 19,886 Reputation points Microsoft Employee

2024-04-15T20:50:38.8166667+00:00

I N

The default setting of 0 for the MIN_CPU_PERCENT value does not directly cause all databases to throttle. However, it can lead to resource contention and uneven distribution of CPU resources among databases within an Azure SQL Database pool.

2 answers

RevelinoB 3,505 Reputation points

2023-07-20T17:31:41.9633333+00:00

Good afternoon Bruno,

To change the MIN_CPU value for a database inside an Azure SQL Database pool, you can use the ALTER DATABASE SCOPED CONFIGURATION statement. This statement allows you to configure various settings for individual databases within the pool, including the MIN_CPU_PERCENT value.

Here's an example of how you can set the MIN_CPU_PERCENT value for a specific database within the pool:

-- Connect to the specific database you want to configure

USE [YourDatabaseName];

-- Set the MIN_CPU_PERCENT value

ALTER DATABASE SCOPED CONFIGURATION SET MIN_CPU_PERCENT = 10; -- Replace 10 with the desired minimum CPU percentage

-- Verify the configuration change

SELECT * FROM SYS.DM_USER_DB_RESOURCE_GOVERNANCE WHERE DATABASE_ID = DB_ID();

In the above example, I've set the MIN_CPU_PERCENT value to 10 as an example. You can replace it with the desired minimum CPU percentage for your database. Keep in mind that the value must be within the range defined by the maximum and minimum values specified at the pool level.

After executing the ALTER DATABASE SCOPED CONFIGURATION statement, you can verify the configuration change by querying the SYS.DM_USER_DB_RESOURCE_GOVERNANCE view, as you did before, to ensure that the MIN_CPU_PERCENT has been set to the desired value for the specific database.

By setting the MIN_CPU_PERCENT value, you can ensure that a certain percentage of the CPU resources will be guaranteed for a particular database, preventing excessive resource contention and potential slowdowns in the system

I hope this helps with your query?
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1 person found this answer helpful.
Bruno Silva 5 Reputation points

2023-07-20T17:44:28.74+00:00

I tried running:

ALTER DATABASE SCOPED CONFIGURATION SET MIN_CPU_PERCENT = 10;

but as a return I got:

Incorrect syntax near 'MIN_CPU_PERCENT'

Bruno Silva 5 Reputation points

2023-07-20T17:45:42.49+00:00

I tried running:

RevelinoB 3,505 Reputation points

2023-07-20T17:53:04.8366667+00:00

Hi Bruno,

Apologies for the confusion caused. It seems that the MIN_CPU_PERCENT option is not available in Azure SQL Database. I apologize for the incorrect information in my previous response.

In Azure SQL Database, the ability to directly configure the minimum CPU percentage for an individual database within a pool is not supported. The CPU resources are managed collectively at the pool level, and each database within the pool shares the available resources based on their workload demands.

If you're experiencing performance issues with a specific database in the pool, you can consider optimizing the queries and workload within that database to reduce CPU consumption. This can be achieved by optimizing query execution plans, improving indexing strategies, or adjusting the workload itself.

Additionally, you may want to monitor the resource utilization of all databases within the pool and consider scaling up the pool by increasing the performance level or vCore count if the overall resource demand is consistently high.

Again, I apologize for the incorrect information provided earlier, and I appreciate your understanding. Let me know if there's anything else I can assist you with!

Bruno Silva 5 Reputation points

2023-07-20T17:56:31.28+00:00

And thinking at the pool level, isn't it possible to set a minimum amount of cpu for all applications?

RevelinoB 3,505 Reputation points

2023-07-20T18:01:32.7766667+00:00

Hi Bruno,

As far as I know. In Azure SQL Database, there is currently no direct option to set a minimum CPU allocation for all databases within a pool. The CPU resources are managed collectively at the pool level, and the distribution of resources among the databases is dynamic based on their workload demands.

However, there are a few strategies you can consider to ensure a minimum level of CPU resources for your applications within the pool:

Monitor and Optimize Workloads: Keep an eye on the performance of your applications and their resource utilization within the pool. Identify any resource-intensive queries or inefficient code and optimize them to reduce CPU consumption. This can help ensure that each database within the pool receives an adequate share of resources.

Scale Up the Pool: If you consistently experience high resource demand across all databases within the pool, you might consider scaling up the pool by increasing the performance level or vCore count. This will provide more CPU resources for all databases, allowing them to handle peak workloads more effectively.

Use Elastic Pool Reservations: Azure SQL Database provides the option of Elastic Pool Reservations, which allow you to pre-purchase resources for a set period of time. By reserving a sufficient amount of CPU resources, you can ensure a guaranteed minimum level of performance for your databases within the pool.

While there isn't a direct setting to allocate a minimum CPU percentage for all applications within a pool, these strategies can help optimize resource utilization and ensure a more consistent level of performance across your databases.

Again, I apologize for any confusion caused earlier, and I hope this clarifies the options available to manage CPU resources within an Azure SQL Database pool. Let me know if you have any further questions!
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Oury Ba-MSFT 19,886 Reputation points Microsoft Employee

2023-07-21T22:47:32.3266667+00:00

@Bruno Silva Please see answer below.

The minimum number of vCores reserved for any database in the pool. Consider setting a min vCores per database when you want to guarantee resource availability for each database regardless of resource consumption by other databases in the pool. The min vCores per database may be set to 0, and is also the default value. This property is set to anywhere between 0 and the average vCores utilization per database.

Customizing min and max vCores for individual databases in the pool is not supported.

Resource limits for elastic pools using the vCore purchasing model

Regards,

Oury
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Oury Ba-MSFT 19,886 Reputation points Microsoft Employee

2023-07-25T17:19:28.0466667+00:00

@bruno silva

Checking if the above answer was helpful. If yes, please mark as accept answer. Otherwise let us know if you need additional clarification.

Regards,

Oury
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How is it possible to set the minimum amount of CPU for a database inside a pool in Azure?

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