System Design Fundamentals
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SQL Normalization and Denormalization

Two opposite techniques, and knowing which one you are doing is most of the skill.

Normalization splits data apart to remove duplication. Denormalization brings it back together to make reads cheap.

Normalization

Normalization organizes tables to reduce redundancy and dependency, by dividing a database into two or more tables and defining relationships between them.

It reduces redundancy, avoiding duplicated data. It improves data integrity, keeping the data accurate and consistent

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Ruslan Iskandarov

Ruslan Iskandarov

· 2 years ago

I didn't understand the section titled "Levels (Normal Forms)"

  • 1NF (First Normal Form): Data is stored in atomic form with no repeating groups.
  • 2NF (Second Normal Form): Meets 1NF and has no partial dependency on any candidate key.
  • 3NF (Third Normal Form): Meets 2NF and has no transitive dependency.
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M

Mohit

· 2 years ago

Under the Key Differences section, it says:

Normalization increases the complexity of the write operations.

However I thought it would increase the read complexity since now we have to do a join to get the same data.

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Srikanth Pisharody

Srikanth Pisharody

· 2 months ago

The 3 Levels of normalization has been dumbed down to single line explanations. There should separate pages for each of these with real world examples of when using a certain level makes sense. This is an important topic and should be addressed in detail.

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T

thandra82

· 2 months ago

  • 1NF (First Normal Form): Data is stored in atomic form with no repeating groups.
  • 2NF (Second Normal Form): Meets 1NF and has no partial dependency on any candidate key.
  • 3NF (Third Normal Form): Meets 2NF and has no transitive dependency.

these are literally single line statements doesnt make sense.