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Difference between "Max Sessions", "Max Concurrent Logins" and "Max Concurrent Requests" RRS feed

  • Question

  • Hi,

    We're experiencing some problems with an Azure S2 instance, which looks like it has to do with the number of open connections. We believe it is a connection leaking somewhere. While researching the issue, I came across a table defining the following for an S2 instance:


    Max Concurrent Requests  = 120

    Max Concurrent Logins = 120

    Max Sessions = 1200

    The error we are getting is "The session limit for the database is 1200 and has been reached".

    The question I have is: What does Max Sessions actually represent? I can understand Max Concurrent Logins as the value for "user connections" in table `sys.configurations`. How is that different from Max Sessions and Max Concurrent Requests?

    I've already looked at the following:

    Max Concurrent Requests Max Sessions Max Pool Size
    https://social.msdn.microsoft.com/Forums/en-US/1dd268fa-45d3-4490-b421-cdbf2a691c3c

    SQL Azure Max Connections
    https://social.msdn.microsoft.com/Forums/azure/en-US/11f3584a-ab71-48cc-9bec-9eb91b2c84c8



    Thanks!


    Monday, August 31, 2015 12:16 PM

Answers

  • Hi Noel,

    When you look at the lifecycle of a connection to database:

    - An active process of logging in to database, not yet completed is using a 'Login'
    - Once the login process has completed and (idle) connection is established, you are using a 'Session'
    - Once you start running a query, you are using both a 'Session' and a 'Request'

    Hope it helps,
    Maja

    Monday, August 31, 2015 1:15 PM