Database System Flashcards
Need to write a new program to carry out each new task
Difficulty in accessing data
Data are represented in the form of table
Relational Model
Become buried rather than being stated explicitly.
Integrity problems
Describe how a record is stored
Physical Level
Multiple file and formats
Data Isolation
the actual content of the database
Instance
Hide the complexity of data structure to represent data in the database
Data Abstraction
Failure may leave the database in inconsistent state
Atomicity of updates
Data is stored in different file formats resulting induplication of file information in different file
Data redundancy and inconsistency
Hard to add new constraints or change existing ones.
Integrity problems
described the database design at the physical level
Physical Schema
described the database design at the logical level
Logical Schema
the overall design of the database
Schema
High level of abstraction
View Level
Describe what data are stored in the database
Logical level
Provides user with an abstract view of data
Database management system
A collection of conceptual tools describing data, data relationship, data semantics and consistency constraints.
Data Model
A collection of interrelated data and a set of program to access those data.
Database Management System
Provides a way to store and retrieve data information that is convenient and efficient
Database management system
Hard to provide access to some user, but not all data
Security Problems
refer to collection of data
Database
To specify database schema
Data-Definition Language
To express database queries and updates
Data-Manipulation Language
Access and manipulate data in existing schema object
DML Statement
Require a user to specify what data are needed and how to get those data
Procedural DMLs
Require a user to specify what data are needed without specifying how to get those data
Declarative DMLs
A statement requesting the retrieval of information
Query
A portion of DML that involves information retrieval
Query Language
deciding on the database schema
Logical Design
deciding on the physical layout of the database
Physical Design
Stores database itself
Data Files
Stores metadata about the structure of the database
Data Dictionary
can provide fast access to data items
Indices
provides pointer to those data items that holds particular value
Database Index
Interprets DDL statement and record the definition in the data dictionary
DDL Interpreter
Translate DML statement in a query language into an evaluation plan
DML Compiler
Executes low level instruction generate by DML Compiler
Query Language Engine
A collection of operation that performs a single logical function in a database application
Transaction
Ensures that the database remains in a consistent state despite system failure and transaction failure
Transaction Management Component
controls the interaction among the concurrent transaction
Concurrency control manager
What happened on 1950’s to 1960’s?
Data processing use magnetic tape for storage
Allowed only sequential access
Used punched card for input
What happened on Late 1960’s and 1970’s?
-Hard disk allowed direct access to data
-Network and Hierarchical data were widely used
-Ted Codd defines relational data model and won ACM Turing Award
-IBM Research begins System R prototype
-UC Berkeley (Michael Stonebreaker) begins Ingres prototype
-Oracle released first commercial relational database
-High Performance Transaction Processing
What happened on 1980s?
-Research relational prototype evolves into commercial system
-SQL become industrial standard
-Development of Parallel and Distributed system contributor: Wisconsin, IBM, Teradata
-Introduction of Object Oriented Database System
What happened on 1990s
-Large decision support and data mining application
-Large multi-terabyte data warehouses
-Emergence of Web Commerce
What happened on 2000s?
-Big Data storage like Google Bigtable, Yahoo PNuts, Amazon
-Introduction of No SQL
-Big Data Analysis beyond SQL like map reduce and friends
