To ensure that every order has a corresponding customer, you would apply a Foreign Key Constraint to the order table. This constraint establishes a link between the order table and the customer table, preventing orders without a matching customer.

In a one-to-many relationship, the entity on the "many" side holds the foreign key. This key establishes the link between the two tables, allowing the "many" side to reference the primary key of the "one" side.

A document-oriented database is best suited for hierarchical data with dynamic schemas. It allows storing complex, nested data structures in a document format (e.g., JSON or XML), making it flexible for evolving data requirements.

Graph databases are the most suitable NoSQL type for graph-based data modeling. They are designed to represent and store data as nodes, edges, and properties, making them highly efficient for managing complex relationships in interconnected data sets.

Version control ensures consistency of data models by tracking changes and allowing users to revert to previous states if needed. It prevents conflicts and discrepancies, providing a stable and reliable model over time.

One advantage of using a Star Schema over a Snowflake Schema is reduced query complexity. In a Star Schema, all dimensional data is stored in a single table, making it simpler and faster for querying compared to the normalized structure of a Snowflake Schema, which involves multiple tables and joins.

A recursive relationship in an ERD allows an entity to be related to itself. This scenario often occurs when an entity has a relationship with instances of the same entity type. It is useful in modeling hierarchical structures and network relationships.

Fact tables in a relational database store aggregated data, often derived from transactional tables. Transactional tables, on the other hand, store detailed, raw data. Recognizing these differences is essential for efficient database design and querying in both OLAP and OLTP environments.

In Slowly Changing Dimensions (SCD) Type 4, a "Historical" table is used to store historical changes. This allows tracking changes over time while maintaining the current data in the main table. This type is beneficial when it's essential to preserve a complete history of changes.

The "row key" in a column-family store is crucial as it uniquely identifies a row. It acts as the primary key for data retrieval, enabling efficient and fast access to specific rows in the column-family.