Noticing huge discrepancies in numbers from Data Warehouse vs. Workspace/AdHoc Analysis. Both Pageviews and Total Seconds Spent are very in line with each other, but Visitors and Unique Visitors are significantly over-represented in Warehouse.
I'm breaking out by Date > New Repeat (sprop) > First Touch Channel > Mobile Device Type > PageName (sprop) : METRICS
Is the issue a result of the dimensions I'm breaking out by?
Data warehouse will not de-duplicate the Visits and Visitors if you are about to calculate it.
Consider the below example:
A visitor (new) come to our site via Search and accessed 3 pages A, B and C.
Same visitor visited our site next day (So, now it is repeat) via Direct and accessed B (Twice) and C.
Below the table in Data Warehouse will look like:
As per Workspace/AdHoc Analysis, For New there are 3 page views, 1 Visit and 1 Unique Visitor for New. But if we add the visits in Data Warehouse it will give you 3 page views, 3 Visits and 3 Unique Visitors.
I.e. Metrics which involves persistence or expiration will be de-duplicated in Data Warehouse but not in Workspace/AdHoc Analysis and thus the difference.