In an ERD, a diamond-shaped symbol is used to represent a relationship between entities. This symbol indicates how entities are connected or related to each other in the database schema. The lines drawn between entities and the diamond symbolize the nature and cardinality of the relationship.

Common strategies for implementing partitioning in a distributed database system include Range partitioning (dividing data based on ranges), Hash partitioning (using a hash function), List partitioning (based on a specified list of values), and Round-robin partitioning (equal distribution without specific criteria). These strategies aid in efficient data management and retrieval in a distributed environment.

Type 6 SCD combines features of Type 1 (overwrite), Type 2 (preserve history), and Type 4 (maintain history in a separate table). This type is versatile and suits scenarios where a comprehensive history, including changes in both dimensions and attributes, is necessary.

For a social networking platform with complex relationships like followers and shared posts, a Graph Database would be suitable. Graph databases excel at handling relationships between entities, making it efficient to represent connections between users and their activities in this scenario.

Immediate consistency is crucial for a financial institution. Therefore, Strong Consistency is the most suitable model as it ensures that updates are instantly reflected across all branches without any delay or inconsistency.

In NoSQL databases, the Strong consistency model ensures that all updates are immediately visible to all clients. This means that once a write is acknowledged, all subsequent reads will reflect that update, providing a high level of consistency in the data.

In a Snowflake Schema, dimension tables are organized in a hierarchical, normalized structure. Unlike a Star Schema, where dimension tables are directly connected to the fact table, Snowflake Schema allows for a more normalized representation of data, reducing redundancy.

SAP PowerDesigner is recommended for its ability to integrate with enterprise software ecosystems, including ERP systems. It also provides robust support for data security and compliance, making it suitable for the stringent requirements of a multinational corporation.

In a Generalization and Specialization hierarchy, a subclass can have multiple superclasses through multiple inheritances. However, this approach introduces complexities and potential issues like ambiguity and data redundancy.

Microsoft Visio offers an advantage with its integration with Microsoft Office applications. This allows users to seamlessly incorporate their database diagrams into other Office documents, fostering better communication and documentation. Its versatility makes it a preferred choice for those already using Microsoft tools.