Articles Posted in the " Extended Events " Category

  • Extended Event duration Millisecond or Microsecond?

    Extended Event duration Millisecond or Microsecond?

    There was a question in titled “module_end extended events duration in microseconds?” that I answered and it was Microsecond in that instance.
    Later on I questioned myself if the duration is always in Microseconds for extended events. I found, it is a mix of Millisecond, Microsecond and some are unknown meaning famous NULL. I wrote below tsql code to determine which is what.

    SELECT package_name,
           DurationUnit= CASE
                             WHEN c.description LIKE '%milli%' 
                             THEN SUBSTRING(c.description, CHARINDEX('milli', c.description),12)
                             WHEN c.description LIKE '%micro%' 
                             THEN SUBSTRING(c.description, CHARINDEX('micro', c.description),12)
                             ELSE NULL
           c.type_name field_type,
           c.column_type column_type
    FROM sys.dm_xe_objects o

  • View Multiple System Health Extended Event Files

    Last week I blogged about increasing retention of System Health session files. In this post I will show how you can open multiple files at once and work with the data as one set.

    If you select multiple System Health extended event files (with extension .xel) and click open each file will open in separate window of SQL Server Management Studio (SSMS).



    You can see here 4 files opened in 4 different windows. Now you cannot sort, group, apply filter, export data from all 4 windows as one data set.



    For opening all these files in one window …

  • SQL Server system_health Session Retention

    As per Microsoft’s books online

    The system_health session is an Extended Events session that is included by default with SQL Server. This session starts automatically when the SQL Server Database Engine starts, and runs without any noticeable performance effects. The session collects system data that you can use to help troubleshoot performance issues in the Database Engine. Therefore, we recommend that you do not stop or delete the session.

    What this article does not tell you is your individual file size is 5 MB and number of maximum rollover file is 4. Meaning you will only get 20 MB of …