Lecture 5: Spatial database and geodatabase Flashcards
Database
A structured set of data that has some connection or relationship to each other
Integrated database
An integrated database is fully embedded in an organizational
structure and has well defined responsibilities for data collection,
maintenance and sharing. It can be either analogue or digital
What are the challenges with non-integrated database?
Data duplication High maintenance costs Poor portability and sharing Non-systematic editing Difficult to implement standards and security features
Digital database
Electronic files that are managed by computer software
Advantages of digital databases
Multiple access methods
Data sharing is more efficient
Redundancy is minimized, and as a result costs as well
Central control and maintenance
Efficient analysis and production of information for decision making
What are the different sources of GIS data?
Maps, tables, user input, Reports, Digital products, images and tables
Database model
The data in the database is are organized using a data model, which is a set of explicit rules for representing the data object and their relationship
What is the hierarchal database model and when it can/cannot be used?
Hierarchal database model is used when there is a one to many method for storing data in a database that looks like a family tree with one root and a number of branches or subdivision
Problem: Linkages in tables must be known beforehand
- It does not work when we have entities that belong to several classes or do not have mutual exclusivity
What is networked database model and what is the problems?
A database design for storing information by linking all records that are related with a list of “pointers”
Problems: It is not adaptable to change
- Linkage tables must be known beforehand
Relational (tabular) database model
- Most commonly used in ArcGIS
- Data is stored in and relationships are created between one or more flat
files or tables where each pair of tables has a field in common, or “key” - Data usually extracted by structured query language (SQL)
What problems can maps present?
Generalization
Deformation
Artificial errors
What are the issues of relevance?
Availability
accessibility
copyright
confidentiality
What is data stream?
Data stream is the process of data encoding and editing
What is metadata and why is it needed?
Metadata is descriptions about the data set Metadata is needed to: - identify geospatial sources - exchange geospatial sources - manipulate geospatial sources - catalogue geospatial resources
What are some problems that can occur when you document data quality?
Location accuracy and precision Attribute accuracy and precision Logical consistency Completedness Data currency Data accessibility
