Azure SQL Server（弹性池）连接缓慢

Question

We ar running a webapplication in Azure Web Apps using a database per customer (multiple accounts per customer). When logging in we connect the user to the correct customer database. This database is also hosted in azure (an elastic pool). It is hosted in the same region (West Europe) as the Web App.

Once the connection is pooled, request times are fast, but the first time a user log's in, the connection still needs to be created an this takes (quiet) a long time.

The connectionstring is build up using a SqlConnectionStringBuilder.

var csb = new System.Data.SqlClient.SqlConnectionStringBuilder();
csb.DataSource = "tcp:******.database.windows.net,1433";
csb.InitialCatalog = "***-***-***";
csb.UserID = "**-**";
csb.Password = "**********";
csb.MultipleActiveResultSets = true;
csb.Encrypt = true;
csb.PersistSecurityInfo = false;
csb.TrustServerCertificate = false;
csb.ConnectTimeout = 30;

_connectionString = csb.ConnectionString;
// Data Source=tcp:******.database.windows.net,1433;Initial Catalog=***-***-***;Persist Security Info=False;User ID=**-***;Password=******;MultipleActiveResultSets=True;Connect Timeout=30;Encrypt=True;TrustServerCertificate=False

Am I doing anything wrong? Or are there some settings in azure to speed up the connect process?

The above request shows the first request to the application of a customer. It therefor includes the EF Migration Seed resulting in the first 2 queries not actually going to the database itself and quite a lot of queries (not all shown here) to the database.

Answer 1

Well, I solved my problem eventualy. Seems i was matching wrong queries within Applications Insights. I installed Stackify and this gives just the little bit more information I needed.

Seem's Entity Framework does some things with the 'master' database. As the user in the connectionstring did not have access to the 'master' database it throws an error. Well, handling that error take's up quite some time on the app-service used and therefor returning slow. It just doesn't fail.

What EF tries to do is determine if the database exist by querying the master database wich is faster then connecting to a non existing database. If it fails because it can not connect to the master database, EF just tries to connect to the database itself. If connection to the database works, it continues normal execution like the seed method.