Dev builds two-sided AI skills marketplace on a single DynamoDB table

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A developer built Skill Exchange, a marketplace for reusable AI skills, using a single-table DynamoDB design to handle sellers, buyers, reviews, and a leaderboard. The key lesson was to define all read access patterns before designing the schema, since DynamoDB lacks joins and restricts queries to a single partition. Global Secondary Indexes (GSIs) were designed to serve multiple access patterns each, with one index powering both the moderation queue and the live marketplace by using a status-encoded partition key. Approving a skill updates a single attribute, atomically moving the item between index partitions without needing separate status flags or scans. The approach also addressed double-payment risks by encoding purchase uniqueness directly into the primary key structure.

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