How to Design MVP Data Schemas That Survive Real Users

A useful MVP schema usually has five layers: identity, tenancy, business objects, transactions, and integration records. Identity describes people and login providers. Tenancy describes the workspace, company, store, or account that owns data. Business objects represent the product’s central nouns, such as projects, listings, orders, appointments, or subscriptions. Transactions capture money and state changes, while integration records preserve the relationship with services such as Stripe, Slack, Zapier, Shopify, or an external database. For example, a customer portal might include users, organizations, organization_members, projects, invoices, payments, and webhook_events. A user can belong to more than one organization, so putting organization_id directly on users would create a limitation that becomes expensive to remove. The organization_members table can hold role, invitation status, joined_at, and invited_by, allowing membership to evolve without changing the identity record. Give important records stable identifiers and timestamps from the beginning. Use created_at and updated_at on business tables, plus domain-specific dates such as paid_at, cancelled_at, published_at, or completed_at where the distinction matters. Keep external IDs in dedicated fields, such as stripe_customer_id or shopify_order_id, and add a uniqueness rule when one external object should map to only one local object. PostgreSQL’s official documentation explains how primary keys, unique constraints, foreign keys, and check constraints protect these assumptions at the database level: PostgreSQL constraint documentation. Avoid storing multiple meanings in one field. A status value such as active can mean enabled, paid, verified, or currently in use, so model those concepts separately when they affect permissions, billing, or reporting. Likewise, do not overwrite important business history simply to keep the table small. A current status column is useful for fast reads, but an event or transition record may be necessary when support, finance, or compliance needs to understand what happened.

Authentication answers who someone is, while authorization answers what that person may do. These should not be collapsed into a single user_type field. A founder may be an administrator in one workspace, a viewer in another, and a customer in a third, so roles belong to the relationship between a user and an account whenever multi-tenant access is possible. A practical minimum includes users, organizations or accounts, organization_members, roles or permissions, and invitations. Store provider identifiers separately from your internal user ID, because a person may later sign in with another provider or change their email address. Never use an email address as the permanent identity key. Email can be unique for login purposes, but it is also mutable, case-sensitive in confusing ways, and not a reliable reference for historical records. Payments need a similar separation. Keep the local customer or account relationship distinct from provider objects such as Stripe customers, payment intents, subscriptions, invoices, and refunds. Store amounts as integer minor units, such as cents for USD, together with currency, rather than relying on floating-point values. For each payment, preserve the provider ID, local order or invoice ID, current state, amount snapshot, and relevant timestamps. The article on integrating Stripe, webhooks, and a database securely covers the payment flow in more detail. Permissions should be checked on the server or trusted data layer, not only hidden in the interface. A button that is invisible to a viewer does not prevent a crafted request from reaching an endpoint. The OWASP Authorization Cheat Sheet recommends denying access by default and validating permissions on every request, principles that apply even to a small MVP.

A connected MVP should treat external services as independent systems, not as extensions of one database transaction. Stripe may confirm a payment after the browser closes, Zapier may deliver an automation after a delay, and a user may press Submit twice before the first request finishes. Your local schema needs enough information to accept these events safely, associate them with the right business object, and show an honest state while confirmation is pending. Create an integration or webhook_events table with fields such as provider, event_id, event_type, received_at, processed_at, processing_status, attempt_count, and error_message. Make provider plus event_id unique when the provider guarantees event IDs. Process an event only once, or make repeated processing harmless. Stripe’s documentation describes idempotency keys as a way to safely retry requests without performing the same operation twice: Stripe idempotent requests. Do not let Zapier become the only copy of an important business fact. If a lead notification fails, the lead should still exist in your database. If a Slack message is delayed, the underlying approval should remain visible in the product. Store the business event locally, then use a connector or job to deliver the side effect and record whether it succeeded. Your interface should represent uncertainty clearly. A payment can be pending, succeeded, failed, or refunded, and those states should not be inferred solely from whether a redirect occurred. Similar rules apply to inventory, onboarding verification, and account provisioning. For a broader treatment of retry, idempotency, and consistency decisions, see resilient integration workflows for an MVP.