Evaluate the need for denormalizing databases

• Denormalization means intentionally adding some redundancy back into a database.
• It is usually done to improve performance.

Advantages

• simpler queries (less SQL JOIN to execute, so faster)
• fewer joins
• faster data retrieval
• useful for reporting systems and read-heavy systems

Disadvantages

• more duplicated data
• harder updates and inserts
• higher risk of inconsistency
• more storage required

When denormalization may be needed

• when performance is more important than strict normalization
• when complex joins are too slow
• when the database is mostly read rather than frequently updated

Evaluation

• Normalization is usually the best starting point because it:
  • reduces redundancy
  • improves integrity
  • avoids anomalies
• Denormalization may be justified when:
  • the system has performance bottlenecks
  • read speed matters more than update simplicity