8 - Data management

Question 1

Data type

Answer 1

How a GIS stores attribute data

Question 2

Database

Answer 2

A database is a collection of interrelated tables in digital format

Question 2

DBMS

Answer 2

Software package that allows us to manage and manipulate a database

Question 3

The primary objective of a database

Answer 3

to collect and maintain information as well as to relate facts and
situations that were previously unconnected.

Question 4

Why is the Flat file outdated in GIS?

Answer 4

because it lacks any method of checking data integrity

Question 5

Hierarchical database pros

Answer 5

• easy to understand
• easy to search
• easy to expand

Question 5

Hierarchical database cons

Answer 5

• define each relation
• difficult to modify the structure
• large index files - extra storage needed
• no many-to-many
• restricted queries
• not used in GIS

Question 6

Hierarchical database model def

Answer 6

a data model in which the data are organized into a tree-like structure. The data are stored as records which are connected to one another through links. A record is a collection of fields, with each field containing only one value

Question 7

Network database model

Answer 7

allows each record to be related to multiple primary records and multiple secondary records

Question 8

Network database pros

Answer 8

• more flexible than H
• many-to-many relation

Question 9

Network database cons

Answer 9

• complex
  -pointers must be defined
• many pointers = more storage
• limited application

Question 10

Foreign key def

Answer 10

one or more attributes that refer to a primary key in another table

Question 11

Relational database def

Answer 11

• data AND the relationships among
  the data are stored in tables
• Provide a flexible approach to linkages between records
• comes close to modelling the complexity of spatial relationships
  between objects

Question 12

Relational database pros

Answer 12

• simple & flexible
• doesn’t have to be complete from outset
• each table independent with key field (Only link with query)
• ease of creation and maintenance
• efficient data management and data processing
• Used in many GIS

Question 12

Primary key def

Answer 12

represents one or more attributes whose values can uniquely identify a record in a table

Question 13

Object orientated database def

Answer 13

Spatial data and all related attribute data for a feature is dealt with as an integrated entity (keeps geometric &
attribute data together as single unit)

Question 13

Relational database cons

Answer 13

• become large and complex

Question 13

OODMS pros

Answer 13

• Data is located in one place
• Easier to update on a consistent basis
• Geometry information stored IN the database along with
  the attributes in a single system!

Question 14

RDBMS weaknesses (reasons for OODBMS)

Answer 14

• Inability to store complete objects directly in database
• Problem dealing with rich data types e.g. sound & video
• Problem with some queries… limitations on geographic
  applications

Question 15

OODBMS cons

Answer 15

• Maintaining values, connections,
  methods, and behaviour for each
  object complex

Question 16

Relational class

Answer 16

Predefined relationships supported and stored in geo-database

Question 17

Many-to-many

Answer 17

Cannot join,
must relate table