In data warehousing, a degenerate dimension is a dimension key that does not have its own dimension table but is instead stored in the fact table. It's essentially a dimension attribute that is treated as a measure due to its significance in analysis. Understanding this is crucial for designing efficient data warehouses.

Dimensional Modeling contributes to data warehouse performance by reducing data redundancy, simplifying complex queries, and providing efficient aggregations. This design approach optimizes query performance and facilitates faster data retrieval, which is crucial for data warehouse efficiency.

In a fact table, surrogate keys are used instead of natural keys to uniquely identify each record. Surrogate keys are system-generated and provide a stable identifier, avoiding the complexities that can arise with changes in natural keys. This enhances the stability and efficiency of the data warehouse.

The process of loading data into a Data Warehouse or Data Mart is known as ETL (Extract, Transform, Load). This involves extracting data from source systems, transforming it into a suitable format, and loading it into the target data repository for analysis and reporting.

The NOT NULL constraint ensures that a column does not contain NULL values. It is used to enforce data integrity by requiring each value in the specified column to be filled with valid data.

In a Generalization and Specialization hierarchy, subtypes inherit attributes from the superclass but may have additional attributes specific to their category. This allows for a more detailed representation of data within the model.

Reverse Engineering in database design is commonly used for generating a database schema from existing code or structures. It involves analyzing an existing database or software to understand its structure and then creating a visual representation of that structure, such as an Entity-Relationship Diagram (ERD).

Aggregation functions like SUM, AVG, MIN, and MAX operate on a set of values. These functions perform calculations on a column of data to produce a single result, such as the sum or average of the values in that column. Understanding how to use aggregation functions is crucial for data analysis and reporting.

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In the context of a social media platform, the design should consider factors such as user roles, privacy settings, post types, and comment threading. This ensures a comprehensive representation of user interactions and content relationships in the conceptual schema.

Denormalization can lead to improved retrieval performance for certain types of queries. By minimizing the need for joins and simplifying data structures, queries that involve reading data become more efficient in a denormalized schema.

Advantages of using inheritance in database modeling include improved data consistency and reduced redundancy. However, disadvantages may arise from increased complexity and potential performance issues, making it crucial to carefully consider when to use inheritance.