Database engine

The database engine is the underlying software that stores and queries the data. Common choices include PostgreSQL, MySQL and SQLite for traditional relational data, and document stores such as MongoDB for flexible records. Two products can look alike on the surface and still behave very differently depending on the engine beneath them.

The engine affects hiring, tooling and how easy it is to move away later. A product built on a widely used engine can be connected to many reporting tools, and most developers already know the query language. A less common engine may lock you into the vendor's own tools.

For a non-technical buyer, the key point is portability and support. If a developer or analyst will work with the data, ask them which engines they are comfortable with. If you only use the product through its interface, the engine matters much less.

• Which engine is it, and which version?
• Can you connect standard tools, such as a reporting tool or a SQL client, directly to it?
• Are extensions or add-ons supported, for example for search or geographic data?
• How would you export all your data if you decided to leave?