Week 1: SDBMS/GIS/RDBMS Flashcards
What are the cons related to RDBMS approach for managing spatial data?
1) No data interdependence: querying requires knowledge of structure of spatial objects
2) Inefficient:
(i) representing spatial info requires a large amount
of tuples
(ii) spatial queries are not directly supported and
require join of several different tables
3) Need to manipulate large tables of points
4) Difficult to perform spatial computations
5) Difficult to define new data types for spatial objects
What are the characteristics of the loosely coupled approach?
1) Separation between spatial and non-spatial data
2) Two systems coexist: a usually relational DBMS for descriptive alphanumeric data & a component for spatial data management
What are the pros and cons of the loosely coupled approach?
Pros:
1) Proper geo-spatial data management
2) Spatial queries are directly supported
Cons:
1) Difficulty in modelling, using & integrating heterogeneous models within the same system
2) Partial loss of basic DBMS functionality (e.g. for querying spatial data
3) Need to learn complex sw packages
What are the characteristics of the integrated approach?
1) Based on DBMS extensibility
2) For geo-spatial applications, extensions to relational DBMS include:
(i) extension of SQL: new spatial types handled as alphanumeric types
(ii) adaptation of usual DBMS functions (indexing, query optimisation) to handle spatial data efficiently
What is the main concept of the integrated approach?
ability to add new types & operations to existing relational DBMS
What are the main points for GIS & SDBMS?
GIS:
1) Classical GIS systems adopt a hybrid management for data
2) Spatial data stored in proprietary (vector) files. Spatial objects in these files are linked to tables containing corresponding attribute information.
SDBMS:
1) adopt an integrated approach
2) Better for data integration but still behind in functionality.
