GIS Data Storage and Management PDF

GIS DATA STORAGE AND MANAGEMENT Biruk G. March 2020  INTRODUCTION TO DBMS  Databases and database systems have become an essential component of everyday life in modern society.  In the course of a day, most of us encount...

GIS DATA STORAGE AND MANAGEMENT Biruk G. March 2020  INTRODUCTION TO DBMS  Databases and database systems have become an essential component of everyday life in modern society.  In the course of a day, most of us encounter several activities that involve some interaction with a database. SOME EXAMPLES  In the past few years, advances in technology have been leading to exciting new applications of database systems.  Multimedia databases  can now store pictures, video clips, and sound messages.  Data warehouses and on-line analytical processing (OLAP) systems  are used in many companies to extract and analyze useful information from very large databases for decision making.  Real-time and active database technology  is used in controlling industrial and manufacturing processes.  Geographic information systems (GIS)  can store and analyze maps, weather data, and satellite images. WHAT IS DATABASE AND DBMS?  Databases are organized collections of interrelated data.  Are managed by a software known as database management systems (DBMS) and shared by multiple applications. WHY DBMS? WHY DBMS?  GIS AND DBMS  Database management systems are an integrated and crucial components of most successful GIS.  DBMSs are used to store, manipulate and retrieve data from a database.  A key element in creating spatial database is database design using a variety of data modeling techniques.  SPATIAL DATABASE  Definition  A spatial database is a collection of spatially referenced data that acts as a model of reality  a database is a model of reality in the sense that the database represents a selected set or approximation of phenomena  these selected phenomena are deemed important enough to represent in digital form  the digital representation might be for some past, present or future time period (or contain some combination of several time periods in an organized fashion) SPATIAL DATABASE  Fundamental database elements  Elements of reality modeled in a GIS database have two identities:  Entity - the element in reality  Object - the element as it is represented in the database  SPATIAL DATABASE  Entity  An entity is "a phenomenon of interest in reality that is not further subdivided into phenomena of the same kind"  e.g. a city could be considered an entity and subdivided into component parts but these parts would not be called cities, they would be districts, neighborhoods or the like  e.g. a forest could be subdivided into smaller forests  SPATIAL DATABASE  Object  An object is "a digital representation of all or part of an entity"  The method of digital representation of a phenomenon varies according to scale, purpose and other factors  e.g. a city could be represented geographically as a point if the area under consideration were continental in scale  the same city could be geographically represented as an area if we are dealing with a geographic database for a state or a county GIS DATABASE REQUIREMENTS  Scale to large sizes (multiple terabytes)  Scale to large number of users (hundreds to thousands)  Provide advanced GIS data models and behavior  Maintain spatial data integrity  Deliver fast data retrieval  Support long transactions and GIS work flows  Support multiple uses and applications  Proven to work through real case studies  GEODATABASE – INTRODUCTION  The Geodatabase has three key aspects:  It is a comprehensive information model and a transaction model for GIS  It is the common application logic used in ArcGIS for accessing and working with all geographic data files and formats  It is a physical instance of a collection of datasets stored in a file system or DBMS GEODATABASE – INTRODUCTION  Geodatabases work across a range of DBMS architectures and file systems, come in many sizes, and have varying numbers of users.  They can scale from small, single-user databases built on files up to larger work group, department, and enterprise databases accessed by many users.  Two types of Geodatabase architectures are available: personal Geodatabases and multi-user Geodatabases.  GEODATABASE - PERSONAL  Personal Geodatabases use the Microsoft Jet Engine database file structure to persist GIS data in smaller databases.  Personal Geodatabases are much like file-based folders and hold databases up to 2 GB in size.  Microsoft Access is used to work with attribute tables in personal Geodatabases.  GEODATABASES - MULTI-USER  Readily scale to extremely large sizes and numbers of users.  Through many large Geodatabase implementations, it has been found that DBMSs are efficient at moving the type of large binary objects required for GIS data in and out of tables.  In addition, GIS database sizes and the number of supported users can be much larger than GIS file bases.  GEODATABASE - KEY DATABASE CONCEPTS  The Geodatabase architecture is based on a series of simple yet essential database concepts.  The DBMS provides a simple, formal data model for storing and working with information in tables.  Users tend to think of the DBMS as inherently open because the simplicity and flexibility of the generic relational data model enable it to support a broad array of applications.  GEODATABASE - KEY DATABASE CONCEPTS  Key DBMS concepts include:  Data is organized into tables.  Tables contain rows.  All rows in a table have the same columns.  Each column has a type, such as integer, decimal number, character, date, and so on.  Relationships are used to associate rows from one table with rows in another table. This is based on a common column in each table, the primary key or the foreign key.  Relational integrity rules exist for table-based dataset AT THE HEART OF ANY GIS THERE IS ALWAYS A STRONG DATABASE SUPPORT