The full answer
PostgreSQL is the default for most business applications. It handles transactions reliably, supports complex queries and reporting, enforces data integrity and has extensions for full-text search, geographic data and vector embeddings, which means one database can often cover several needs.
MongoDB fits data that varies a lot in shape, such as content, product catalogues with many attribute types or event logs. Redis is used alongside a primary database to speed up frequent reads, manage sessions, power leaderboards and handle background job queues.
For AI features, embeddings can be stored in PostgreSQL using pgvector, keeping everything in one place, or in a dedicated vector database such as Pinecone when scale or search features justify it.
Creuto designs the data model early, because it is one of the hardest parts of a system to change later. Indexing, backups, point-in-time recovery, encryption at rest and access control are configured as standard.
Managed database services from AWS, Azure or Google Cloud are generally preferred, as they handle patching, replication and backups and reduce operational risk.