Change Details

Currently on per-domain uniques, fresh sessions computation named `offset` counts fingerprinted sessions having made: - 1 request with no cookies set (`nocookie IS NOT NULL`) - 0 request with some cookies set (`nocookie IS NULL`). This way of computing the offset undercounts the fresh sessions. While making sure we count only devices having made 1 request with no cookies set (`nocookie IS NOT NULL`) is correct, restricting the number by counting only devices having made 0 other request prevents counting devices whose "fresh" session includes more than 1 hit, about 10% of the offset.

Currently on per-domain uniques, fresh sessions computation named `offset` counts fingerprinted sessions having made: - 1 request with no cookies set (`nocookie IS NOT NULL`) - 0 request with some cookies set (`nocookie IS NULL`). This way of computing the offset undercounts the fresh sessions. While making sure we count only devices having made 1 request with no cookies set (`nocookie IS NOT NULL`) is correct, restricting the number by counting only devices having made 0 other request prevents counting devices whose "fresh" session includes more than 1 hit, about 10% of the offset. Move to production: - Add a row in documentation about the change in [[ https://wikitech.wikimedia.org/wiki/Analytics/Data_Lake/Traffic/Unique_Devices#Changes_and_Known_Problems_with_Dataset | this page ]]

Currently on per-domain uniques, fresh sessions computation named `offset` counts fingerprinted sessions having made: - 1 request with no cookies set (`nocookie IS NOT NULL`) - 0 request with some cookies set (`nocookie IS NULL`). This way of computing the offset undercounts the fresh sessions. While making sure we count only devices having made 1 request with no cookies set (`nocookie IS NOT NULL`) is correct, restricting the number by counting only devices having made 0 other request prevents counting devices whose "fresh" session includes more than 1 hit, about 10% of the offset. Move to production: - Add a row in documentation about the change in [[ https://wikitech.wikimedia.org/wiki/Analytics/Data_Lake/Traffic/Unique_Devices#Changes_and_Known_Problems_with_Dataset | this page ]]