Hi

As you've rightly said the cost of delta sharing is not in the compute but in the egress costs. I would also ignore the GetObject costs as these again will probably be negligible, around $0.0004 per 1000 get object requests. 

So the egress charges is where you may need a solution. Has this been rolled out yet? and do you have a concept of the scale of the likely egress bill. Again you have a certain amount of egress for free, so it may be worth monitoring to see if it's actually a sizeable amount. Remember you'll only be paying egress if it's to a different cloud/region. if you do need to so this I think you would look to query the system audit table for query numbers by user by table. I would then create a reference table of all the relative table sizes in my catalog and use this to apportion costs.

Query to get to how many times a user has used the delta share

SELECT

 event_time,

 event_date,

 action_name,

 user_identity.email                          AS recipient_email,

 source_ip_address,

 request_params['share']                      AS share_name,

 request_params['schema']                     AS schema_name,

 request_params['name']                       AS table_name,

 response.status_code                         AS status_code,

 response.error_message                       AS error_message

FROM system.access.audit

WHERE action_name LIKE 'deltaSharing%'

 -- Uncomment and set a share name to filter to a specific share:

 -- AND request_params['share'] = '<your_share_name>'

 AND event_date >= current_date() - INTERVAL 30 DAYS

ORDER BY event_time DESC

The following is a reference of the actions:

I hope this helps.

Thanks,

Emma