Data modeling

• Table for Actors

• E.g., store, customer, seller

• Table for Actions of actors

• E.g., customers make orders, complains, returns

• Table for properties of actors that don’t fit to 2D diagram

• E.g., possible payment methods for customer

• Table for properties of actions that don’t fit to 2D diagram

• E.g., possible reasons for return

Normalization

• It's a Optimization technique in relational databases

• Normalization: separate tables for redundancy reduction

• E.g., doc, doctor, med doc
• Cons: You know less from only one table. Have to read more than one table
• Denormalization: application of JOINS to integrate tables

Normalized data

• Minimizes storage spaces
• Requires two queries to get data from different sources (tables, collections)
• Easy to perform updates! Need to change only one source of data
• Good approach when the data storage is expensive! And the performance is not important
• Doubles the traffic with double queries (two transactions)! Increseases latency

Denormalized data

• Data is duplicated in order for a source to container all the information needed!
• Only requires one transaction to fetch the complete data
• Improves the performance!
• Downside is that in order to update data, many sources must be updated