Azure SQL DB P4 Not Scaling Properly - azure

Question

I upgraded my azure SQL db from P2 250 dtus to P4 500 dtus.
But, during heavy load again we are facing dropped connections and overall performance degradation.
According to me, the number of concurrent requests become too much and it stars dropping connections.
What i understood was p2 has 400 concurrent workers whereas p4 has 800.
https://learn.microsoft.com/en-us/azure/azure-sql/database/resource-limits-dtu-single-databases?view=azuresql
These concurrent workers are not related to dtus as now my dtus in P4 is 40-45% under heavy load also.
Can we get some data or logs to check the current concurrent workers?
Is there any other way to check it.?
Is that's the main reason for dropped connections and performance degradation?

Answer 1

Can we get some data or logs to check the current concurrent workers?
Is there any other way to check it.? Is that’s the main reason for
dropped connections and performance degradation?
You can Monitor and fetch logs and metrics of your Azure SQL DB by selecting the Metrics like below :-
Here, I am checking successful connections to understand the session metrics and worker percentage to understand if the number of requests or queries are affecting the performance.
You can also use various metrics based on your DTU by changing the metrics like below :-
In order to troubleshoot the performance degradation, You can make use of Azure Diagnostics to solve or get an insight like below :-
I selected High CPU utilization which gave me a recommendation to diagnose the issue and also a T-SQL query that can be run inside Azure SQL query editor or SSMS directly.
As, You have faced issue with scaling, You can also try to diagnose by selecting the option below :-
You can connect to your Azure SQL server in SSMS and query the log data directly to get the worker or sessions.
You can query > # sys.dm_db_resource_stats table in SSMS or query editor and get > max_worker_percent
which will give you - Maximum concurrent workers (requests) in percentage of the limit of the database’s service tier.
Refer below :-
Select * from sys.dm_db_resource_stats;
And query execution graphs metrics like below :-
You can also find insights and improve performance with options below:-
You can enable Azure Monitor and monitor your SQL server and all the DB’s together and find more insight on the concurrent workers and all data from sys.dm_db_resource_stats like below without having to log into SSMS :-
Go to Azure Monitor > select SQL from left tab > Create new profile :
You can add one Ubuntu 18.04 Linux VM to fetch the logs and data from all your SQL Server databases like below for monitoring :-
In this manner all your data will be managed in a centralized monitoring pane in Azure Monitor.
Reference :-
sys.dm_db_resource_stats (Azure SQL Database and Azure SQL Managed Instance) - SQL Server | Microsoft Learn