RELATIONAL DB AND MYSQL INSIGHT

Outline

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Relational DB

Database requirement

MySQL

Relational database management system

1. Purpose2. Normalization

● Wikipedia : A relational database management system (RDBMS) is a

database management system (DDMS) that is based on the relational

model as introduced by E. F. Codd, of IBM's San Jose Research

Laboratory. Many popular databases currently in use are based on the

relational database model.

● Relational database theory uses mathematical terminology, which

are roughly equivalent to that of Normalization:

RDBMS ~ NORMALIZATION

History

NORMALIZATION

• Normalization was first proposed by Codd as an integral part of the relational model.

• It encompasses a set of procedures designed to eliminate nonsimple domains (non-atomic values) and the redundancy (duplication) of data, which in turn prevents data manipulation anomalies and loss of data integrity.

NORMALIZATION PROCESS

Normal Form

Database Requirement

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Requirement?

• Much depends on the application However we can think of something like– In application level:

• Speed (performance)

• Availability

• Scalability

– In transaction level: • ACID (atomicity, consistency, isolation, durability)

– Something else?: • Compression , etc ….

Just clarify the ACID

• Atomicity:– All or nothing– One part of the transaction fails (for failures, errors,

crashes), the entire transaction fails

• Consistency:– Bring database from a valid state to another

• Isolation:– The effect of an incomplete transaction might be or might

not be visible to another

• Durability:– The effect of a completed transaction must be stored

permanently.

MYSQL

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Logical architecture

How does MySQL handle queries?

• Concurrency control– Locking (READ, WRITE)– Table lock and row lock

• Concurrency control– Locking (READ, WRITE)– Table lock and row lock

• Transaction– Isolation level (remember ACID?)

Performance

• Depends on:– Table design

• Schema• Index

– Query• Some query beats all index• Query covered index

– Storage engine• Sometimes affect performance

much more than hard ware– Locking strategy– Etc, …

– Hardware• RAM (should be enough to store

index)• Hardrive, etc…

Availability

GLHF