Which aspect of a shapefile limits its effectiveness compared to a geodatabase?

The aspect that limits the effectiveness of a shapefile compared to a geodatabase is its support for relational data models. Shapefiles are a simple data format for storing geographic features but have limitations when it comes to advanced data management capabilities. They do not inherently support the relationships between different types of data. In contrast, a geodatabase can effectively manage complex relationships using relational data models, allowing for the organization of data in a way that can represent more sophisticated interconnections and dependencies.

This lack of support for relational data models in shapefiles makes them less flexible for projects that require more advanced data management practices, such as maintaining related tables, association of different feature classes, and comprehensive data integrity rules, which can be seamlessly implemented in a geodatabase. Therefore, while shapefiles can be useful for many simple applications, their inability to effectively handle related data is a significant limitation compared to a geodatabase.