In NoSQL databases, conflict resolution is a technique used during eventual consistency to reconcile conflicting versions of data. This is crucial in distributed systems where different nodes might have different versions of the same data due to network delays or partitions.

Collaborative features in ER diagram tools include real-time collaboration on the same diagram, allowing multiple analysts to work simultaneously. Commenting and annotation features enhance team communication, while role-based access control ensures that team members have appropriate permissions. Automated code review helps maintain the quality and consistency of the database schema. These functionalities improve efficiency and coordination among team members.

A composite attribute is one that can be divided into smaller, independent sub-parts, each with its own meaning. In contrast, a simple attribute is indivisible and represents an elementary piece of data. Composite attributes provide a way to model complex information in a database.

Applying aggregation functions to a dataset in a database results in a summary or statistical outcome. Instead of displaying detailed records, these functions provide valuable insights into the dataset, such as total, average, maximum, minimum, or count, helping in the analysis and interpretation of the data.

One challenge of using compression techniques in database systems is the increased processing overhead. Compression and decompression processes require additional computational resources, and striking a balance between storage savings and processing speed is crucial in database design.

A common challenge when using Key-Value Stores for complex data structures is the difficulty in representing relationships between data. Unlike relational databases that excel in handling complex relationships through join operations, Key-Value Stores may face challenges in maintaining such associations directly.

When choosing between range-based and hash-based partitioning, hash-based is advised for uniform distribution and to avoid hotspots. Range-based is suitable for queries involving specific data ranges. The decision depends on the access patterns and distribution goals.

Version control handles rollback by allowing users to manually revert changes to a specific commit. This ensures flexibility in undoing undesirable modifications and restoring the data model to a previous state while maintaining a record of version history.

The primary data structure used in document-based modeling is JSON (JavaScript Object Notation). JSON allows for flexible and hierarchical data representation, making it suitable for storing and retrieving complex data structures. Document databases leverage this format to organize and query data efficiently.

In a relationship with a modality of "Optional," it means that the relationship is optional for all entities involved. This implies that an entity can exist without being associated with another entity through the specified relationship.