Design a **data model** (logical schema) for an advertising platform. Include core entities such as: - Business/account (advertiser) - Campaign and budget - Ad group / line item (if applicable) - Creative and assets - Targeting (audiences, geo, device, etc.) - User (or user identifiers) and privacy constraints - Delivery logs: impressions, clicks, conversions Explain: - Key relationships (1:N, N:M) and how you represent them. - How the schema supports the major flows: 1) **Intake/creation** flow (advertiser creates campaigns/creatives) 2) **Serving** flow (ad selection at request time) 3) **Tracking** flow (impression/click/conversion logging and attribution) - Any indexing/partitioning choices you would make for scale and reporting.