Shared Flashcard Set

Details

COMP3017 - Lecture 2 (A) - Data
COMP3017 - Lecture 2 (A) - Data
22
Computer Science
Undergraduate 3
05/01/2014

Additional Computer Science Flashcards

 


 

Cards

Term
What are some basic Data Types?
Definition
  • Numeric
  • Boolean
  • Enumerated
  • Data and Time
  • User-defined
Term
What are some examples of operations on Data?
Definition
  • Comparison
  • Arithmetic
  • Fuzzy Searches
  • Retreive all documents that contain a given word
  • Find a picture that contains blue sky
Term
What is a data domain?
Definition
  • The set of all values that may be taken by a particular item of data. eg:
    • UK_TOWNS: Aberdeen, London, ...
    • GENDER: Male, Female
    • PERSON_WEIGHT: 0-130kg (to 2 s.f.)
Term
What is the Entity/Relationship model definition for Domain?
Definition
Each simple attribute of an entity type is associated with a value set, or domain, which speicifies the set of values that may be assigned to that attribute for each individual entity.
Term
What are is the Relational model for a domain?
Definition
  • A domain is a set of atomic values
  • By atomic, we mean that each value in the domain is indivisible as far as the relational model is concerned
  • A common method of specifying a domain is to specify a data type from which the data values forming the domain are drawn
Term
An example of Rows, Columns and Domains.
Definition
[image]
Term
What are the options to enforce type constraints in DBMS?
Definition
  • Some SQL Databases can enforce domain constraints
    • Column constraints or CHECK constraints
    • Referential integrity constraints
    • Enumerated lists
  • It's also possible to follow the procedural approach, where you can code your own checks within the application program
Term
What are some Complex Model Objects?
Definition
  • Unstructured
    • Bitmap Image (BLOB)
    • Long text string (BLOB or GLOB)
  • Structured
    • Defined by use of type constructors in an OODBMS
    • The most basic constructors are atom tuple and set
    • Relationships between objects established during an Object ID (OID)
Term
What are abstract data types?
Definition
  • The OO concept that allows construction of an arbitrarily complex object
  • Abstract data type models classes, each with
    • A name
    • A collection of operations (Methods)
    • A representation
  • Abstract data typing supports a much more natural representation of real world problems
  • Support for (some) complex objects has been added to relational DBMSs
Term
What are the types of Time Density?
Definition
  • Granularity is important in time (Day/Minute)
  • Time Density: Discrete
    • Timeline is isomophic ¬†to integers (Integers have total order)
    • Timeline is composed of fixed periods termed chronons
    • Between each pair of chronons is a finite number of other chronons
  • Time Density: Dense
    • Time is isomorphic to rational numbers (Ratinoal Numbers have a partial order)
    • Infinite number of Chronons
  • Dime Density: Continuous
    • Time is isomorphic to real numbers (Real numbers have total order)
    • Infinite number of Chronons¬†
Term
What are some reasons for storing times in a Database?
Definition
  • Various times might be associated with an event that appears in a database
  • The valid time of a fact - when the fact is true in reality
  • The transition time of a fact - when the fact is current in the database, and can be retreived
  • Both of these (bitemporal)
Term
What does the TSQL include?
Definition
  • Retreival of timestamps
  • Retreival of temporally ordered information
  • Using the TIME-SLICE clause to specify domain
  • Using the GROUP BY clause for modified aggregate functions
  • A WHEN clause:
    • i.e. SELECT {select-list} FROM {list of relations} WHERE {where-clause} WHEN {temporal close}
    • Temporal comparison operators include BEFORE/AFTER, FOLLOWS/PRECEDES, DURING, EQUIVALENT, ADJACENT, OVERLAPS
Term
What are some examples of Spatial Data Types?
Definition
  • Points
  • Regions
    • Boxes
    • Quadrangles
    • Polynomial Surfaces
  • Vectors
Term
What are some operations included in spatial data?
Definition
Lenght, Intersect, Contains, Overlaps, Centre
Term
What are some applications of Spacial Data?
Definition
  • Computer Aided Design (CAD)
  • Computer Integrated Graphics
  • Geographic Information Systems (GIS)
  • For these systems, the properties of interest would include:
    • Connectivity
    • Adjacency
    • Order
    • Metric relations
Term
What are some characteristics of Spatial Data in systems dealing with space?
Definition
  • Data objects may be highly complex
  • Data volumes may be very large
  • Data may be held in real time
  • Performance is not easy to achieve
  • Access is likely to be through specialised graphical front ends; Operator skils are key
  • Query processing will not be performed using SQL
Term
What are some characteristics of Textual Data?
Definition
  • Text data may be already in machine-readable form, from a word-processor, spreadsheet or other source
  • May be reading using OCR techniques
  • Text data is essentially unstructured, and an index of some kind needs to be built
    • By human, or automatically¬†
Term
What are some examples of Textual Data?
Definition
  • Markup Languages do give some structure to a document (HTML for web)
  • XML (and predecessor SGML) allows a programmer to create portable documents that contain structured data
    • Can also create new markup languages
  • Character large objects (CLOBs) are now commonly supported by vendors
    • Able to store and handle text documents in addition to standard data
    • Provision of text and retrieval facilities
Term
What are some characteristics of BLOBs?
Definition
  • Binary Large Objects
  • No semantics attached
  • Examples are text or images
Term
What characteristics do Image databases require?
Definition
  • Image analysis and pattern recognition
  • Image structuring and understanding
  • Spatial reasoning and image information retreival
  • Mainstream DB vendors now adding support for BLOBs and access using QBIC (Query by Image Content)
Term
What are some characteristics of Audio Data?
Definition
  • Digitised sound
    • Stored in various formats (WAV, MP3)
    • Consumes large amounts of storage
    • Comparison techniques normally used
  • MIDI (Musical Instrument Digital Interface)
    • More compact than digitised audio
    • Consists of a sequence of instructions: Note_On, Note_Off, Increase_Volume
    • Interpreted by Synthesiser
Term
What are some characteristics of Video Data?
Definition
  • One of the most space hungry formats of all
    • Images stored as sequence of frames
    • Each frame can consume over a megabyte
    • Frames typically played back at 24-30fps
  • To integrate video and audio, interleaved file structures incorporate times sequencing of audio/video playback
    • Microsoft AVI
    • Apple Quicktime
Supporting users have an ad free experience!