Why These Use Cases Belong in One Database
Every use case on this page has the same underlying shape: the value is in the relationships, but the relationships alone are not enough. Fraud analysts need the transaction graph and the time series of account behavior. Recommendation engines need the interaction graph and the vector embeddings that place items in semantic space. Knowledge graphs need entity relationships and the full-text search that gets a user to the right entity in the first place.
The conventional answer is polyglot persistence: a graph database for the edges, a vector store for the embeddings, a time-series database for the metrics, a search index on top, and an application layer stitching them together. That architecture works, but the cost is paid continuously. Every query that spans two stores becomes an application-level join. Every write becomes a distributed write with no shared transaction. Consistency between the graph and the index is now your problem, and the latency budget is spent on network hops rather than on the query itself.
ArcadeDB stores all six models in a single engine with a single ACID transaction boundary. A fraud query can traverse a graph, filter on a time-series window, and rank by vector similarity in one statement, against one copy of the data, in one transaction. That is the property that connects every use case below: they are not nine separate products, they are nine shapes of the same engine.