2003 SJSU -- CmpE L1-S1 Infinite R-DB Database Design Dr. M.E. Fayad, Professor Computer Engineering Department, Room #283I College of Engineering San José State University One Washington Square San José, CA 95192-0180 http://www.engr.sjsu.edu/~fayad, [email protected]
Database Design. Dr. M.E. Fayad, Professor Computer Engineering Department, Room #283I College of Engineering San José State University One Washington Square San José, CA 95192-0180 http://www.engr.sjsu.edu/~fayad, [email protected]. Lesson 1: Infinite Relational Database. 2. - PowerPoint PPT Presentation
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View level presentation of the data: Science, Art, or both (discussion)
We will illustrate examples from different computer fields, such as computer graphics, for view level presentation of complex data, especially spatiotemporal data, such as realistic display of images and movies. 6
• Relation – table(Each table has a name and defines a relation)
• Relational scheme – top row / list of attributes(The top row of a table is called an attribute name)(The ordered set of attributes of a table is called a relation scheme.)
• Arity or dimension – number of attributes of a relation(We will use arity and dimension interchangeably with a preference for dimension in the case of spatiotemporal relations.) 8
• Database schema – set of relation names and schemes• Tuple / Point – each row below the scheme
(we will use these two terms interchangeably with a preference for point in the case of spatiotemporal relations.
• Instance – the set of tuples in a table(Each row describes an instance of the scheme.)(Please remember a relation schemes are usually fixed while a relation instances may change over time due to database updates.) 9
SSN Surname First Name(s) Telephone Number123-45-6789 Doe Jane Q. 512-555-1234987-65-4321 Fulano Juan 210-543-9876567-89-0123 Roe Richard Rodney 512-987-6431
Name the relations! What is arity of each relation? What is the relation scheme of each relation? What is the database scheme? How many tupls in each of the relation? How many instances of each of these relations?
Streets contains pairs of street names and (x,y) points such that the point belongs to the street. There are an infinite number of (x, y) locations associated with each street.
Example: Crops(Corn,Rye,Sunflower, Wheat)
Crops contains all possible combinations of four crops that a farmer could plant. There are an infinite number of tuples in any instance of this relation.
Temporal Data Type (1)The user-defined temporal data type is a time representation specially designed to meet the specific needs of the user. For example, the designers of a database used for class scheduling in a school might be based on a "Year:Term:Day:Period" format. Terms belonging to a user-defined temporal data type get the same query language support as do terms belonging to built-in temporal data types such as the DATE data type.
The spatiotemporal is used to indicate that the modified concept concerns simultaneous support of some aspect of time and some aspect of space, in one or more dimensions.
Database contains the database itself, the definition or
description of the database structure and constraints
The definition is stored in the system catalog which contains the information, such as structure of each file, the type and storage format of each data item, and various constraints on the data.
The information stored in the catalog is called meta-data.
Sharing of data and multiuser transaction processing
A multiuser DBMS must allow multiple users to access the database at the same time.
Concurrency control – to ensure that several users trying to update the same data do so in a controlled manner so that the result of the updates is correct.
Providing persistent storage for program objects and data structures
In OO Database Systems, an object said to be persistent if it survives the execution of program execution and can be later retrieved by another program.
Compatibility – OODBs offer data structure compatible with one or more OO programming languages
Traditional DB systems often suffer from the so-called impedance or mismatch problem 31
a. A view is a way of presenting data to a particular group of users.
b. Any relation can be presented by multiple views
c. Arity = the number of columns in the relation.
d. An instance = any row of a relation
e. Spatial database is a database that supports some aspect of time, not counting
f. Spatial data in the form of two- or three-dimensional images.
g. Spatial data is any information about the location and shape of, and relationships among, geographic features. This includes remotely sensed data as well as map data. 35