Designing a MongoDB schema for large SQL migrations can be challenging due to the lack of codified relationships and data access patterns, making it difficult to gather insights through manual effort. PeerIslands has developed a pre-migration analysis approach that automates this process, providing valuable insights into designing the optimal schema on MongoDB. This approach analyzes data relationships, cardinality, query patterns, table metadata, indexes, and metrics from SQL databases such as Oracle, MySQL, MS SQL, and Postgres to inform schema design decisions. By leveraging database metadata and automated queries, PeerIslands aims to save time for users and prevent incorrect schema designs, ultimately accelerating the SQL migration journey.