RDBMS Data Modeling - Primary key
Table of Contents
1 - About
A Primary Key identify:
- the unique identifier of a single instance
- doesn't change over time. If the primary key has a chance – however remote – of changing, well, then it is NOT the primary key. This would be like you changing your DNA halfway through your life.
2 - Articles Related
3 - Sequence vs business key as primary key
Sequence as primary key
3.1 - Disadvantage
- You can't search on the business key in an external table.
- You need to do an extra action to get the primary key (join in SQL or show the information on the screen)
3.2 - Advantages
- Gain on IO in the internal table but also in the external table
- If the grain of a (external|dimension) table changes, you don't need to add a column in the fact table