Recursive purge is not recursive

[EvanMulawski]

Invoking DurableTaskClient.PurgeInstanceAsync with PurgeInstanceOptions.Recursive = true does not result in sub-orchestrations being purged. The documentation for this method states that sub-orchestrations should be purged when this flag is set.

Example:

var purgeInstanceOptions = new PurgeInstanceOptions
{
    Recursive = true
};

await client.PurgeInstanceAsync("my_instance_id", purgeInstanceOptions);

with rows in the Instances table that have ParentInstanceID=my_instance_id (in addition to the required InstanceID=my_instance_id row that has a RuntimeStatus of Completed, Terminated, or Failed), executes the following SQL:

declare @p1 dt.InstanceIDs
insert into @p1 values('my_instance_id')

exec dt.PurgeInstanceStateByID @InstanceIDs=@p1

(Stored procedure PurgeInstanceStateByID only uses the provided InstanceIDs - it does not perform a recursive CTE.)

[cgillum]

Thanks for bringing this up. Now that I'm looking at the code, I suspect it also may not be implemented for the other storage backends (including Azure Storage).