是否可以限制.NET中数据库连接的总数？

Question

I have an API server that interacts with an Azure-hosted PostgreSQL database instance. There are a large number (>50) of postgres databases on that one postgres server. Any given API request may have to interact with any given database.

Unfortunately, our Azure plan for Postgres only allows 50 connections. I regularly have requests fail because Postgres won't accept more. My ADO.NET connection pool is still holding onto database connections for recently used databases, while connections to other databases error out.

I've tried setting the Max Pool Size on my connection strings, but it appears that the connection pool limit is applied per database , not per server . I still need as much pooling as I can get, opening new connections can take >1500ms, which is beyond my SLA if it happens on every request.

Is there a way to ask .NET to never open more than 50 database connections, either per server or total?

Answer 1

Set Max Pool Size and instead of connecting to a separate database connect to the same database on the server and then execute the \\connect statement to change to the desired database. The following code fragment demonstrates creating an initial connection to the master database and then switching to the desired database specified in the databaseName string variable.

// Assumes that command is a NpgsqlCommand object and that  
// connectionString connects to master.  
command.Text = "\connect DatabaseName";  
using (NpgsqlConnection connection = new NpgsqlConnection(  
  connectionString))  
  {  
    connection.Open();  
    command.ExecuteNonQuery();  
  }