Physical Data Modeling Flashcards

What is the primary purpose of a physical data model?

Answer: To specify how data will be stored in a specific DBMS including tables, columns, indexes, and constraints

A physical data model specifies the actual implementation details — table names, column data types, indexes, partitioning, and storage parameters — for a specific target DBMS.

When transitioning from a logical to a physical data model, what typically changes?

Answer: Entity names become table names, attributes become columns, and DBMS-specific data types are assigned

Moving to physical design involves renaming entities as tables, mapping attributes to typed columns, resolving relationships into foreign keys, and adding indexes and constraints.

What is a clustered index and how does it differ from a non-clustered index?

Answer: Clustered physically orders table rows by the index key; non-clustered creates a separate pointer structure

A clustered index determines the physical sort order of rows in the table itself, while a non-clustered index maintains a separate structure with pointers back to table rows.

What is table partitioning in physical data modeling?

Answer: Dividing a large table's rows into segments based on a partition key to improve performance and manageability

Table partitioning divides a large table into smaller, manageable segments (partitions) based on a key such as date range or region, improving query performance and data maintenance.

In physical data design, what is the purpose of a column constraint CHECK?

Answer: To restrict the range or set of valid values that can be inserted into a column

A CHECK constraint enforces a condition on column values at the database level, rejecting any insert or update that violates the rule.

What does 'data type alignment' mean in physical data modeling?

Answer: Choosing DBMS data types that accurately represent the logical domain while optimizing storage

Data type alignment means selecting the most appropriate DBMS-specific data type that matches the attribute's domain, constraints, and expected value range while minimizing storage.