Extended Event duration Millisecond or Microsecond?
July 23, 2017
There was a question in dba.stackexchange.com 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 p.name package_name, o.name event_name, c.name event_field, 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 END, c.type_name field_type, c.column_type column_type FROM sys.dm_xe_objects o JOIN sys.dm_xe_packages p ON o.package_guid = p.guid JOIN sys.dm_xe_object_columns c ON o.name = c.object_name WHERE o.object_type = 'event' AND c.name ='duration'
Below is a snippet of the result set from a SQL 2016 SP1 server. If you look at the DurationUnit column and you can see 3 different values.
For NULL ones I find the best option is to run (if possible with start and end time) and find what the unit is.
I ran the same query against vnext (SQL 2017) SQL Server and confirmed we will carry the same confusion to the future.