Knowing number of extents processed by a Kusto function

user_5057753 0
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Lets say I have a Kusto function that I have not written and I am only supposed to execute it , is there way of knowing exactly how many extents it has processed (number of unique extent ids) ? I am not supposed to modify the function , so I can't include extent_id() function inside it and if I pipe extent_id() outside the function it just returns something like 00000000-0000-0000-0000-000000000000.

i.e. if I try to following

myfunction() | extend ext_id = extent_id() | take 10

It just gets me 00000000-0000-0000-0000-000000000000.

azure-data-explorer
1 Answers

The output of .show queries (filtered by the client request ID of your query's execution) includes a column named ScannedExtentsStatistics, which includes that information.

The reason for the empty guid you're seeing is the logic inside the stored function you're invoking.

See: https://docs.microsoft.com/en-us/azure/data-explorer/kusto/query/extentidfunction

Applying this function to calculated data that isn't attached to a data shard returns an empty guid (all zeros).

user_78618070
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