4. History
● 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
5. 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.
9. 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 ….
10. 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.
13. 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?)
14. 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…
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