This article helps in understanding basic concepts of Geodatabase. At the end of this article you will be answer the following questions.
What is Geodatabase
What type of data can be stored in it?
Different types of geodatabase
What is Geodatabase (GDB)?
Geodatabase is one of the ESRI’s standard data storage format. It is widely used in ESRI’s proprietary software i.e., ArcGIS.
It eliminates using of separate files and formats for storing information such as points, lines, polygons.
Though above shapefiles (points, lines and polygons) are still widely used by many users, working with geodatabase is less messy as all information can be stored as a single dataset.
“According to ESRI – It is a collection of several types of geographic datasets in a common file system folder such as microsoft database or any other relational database.”
However, it is important to understand that a GDB is more than mere collection of data sets as there are many other things it can accomplish.
Following are some of the key points related to geodatabase.
It is a native data structure of ArcGIS used for storing and managing the geographic data.
The data is stored using a data base management system or file system in a GDB, and it can be accessed directly using ArcGIS or with SQL commands.
GDB uses an information model which consists of a series of tables for storing and handling different data sets i.e., feature classes, raster data and attribute information.
The tables are linked using additional objects, with which relation between the objects is maintained i.e., spatial relationships, spatial integrity etc.
Other than the feature data sets, rasters and attributes GDB also supports working with other types of files such as autocad, TIN, GML etc., as a part of its application oriented logic design.
GDB uses a transaction model for managing workflow in GIS.
What Type of Data is Stored in Geo-Database?
GeoDatabase – Elements
As already discussed in the above section, A geodatabase is collection of different types of datasets.
Following are three different types of data which is stored in a geodatabase.
Feature classes (consists of variety of shape files)
Raster data (comprises continuous data sets made with imagery)
Attribute Information (characteristics and properties/details of features in a data set)
How Geo-Database is Designed?
In simple the design of a GDB starts with collection and storing of different types of data sets for building the database.
After collection, the GDB is extended by adding the functionality such as topology, network etc., to model the behavior of data and maintain integrity and spatial relationships.
All 3 fundamental types of data are stored using tables in a GDB.
ESRI help section is a good place to explore more about the
architecture, fundamentals of storage and design of GDB.
What are Different Types of Geo-Database?
There exist 3 different types of geodatabases.
In file geodatabase, data is stored in the form of files of separate folders. As per ESRI documentation, a file geodatabase can be used for storing and handling data as much as up to 1 Terabyte. Further, file GDB is recommended to the users over personal geodatabase. This database is suitable for single user or for small work groups and applications.
In case of personal geodatabase, all data is stored using Microsoft Access database format. The size of this data base is limited only to 2 Gigabytes (2GB). This is also suitable only for individual users or for small groups and applications.
Enterprise geodatabases are also known as multi user data bases. These have unlimited memory and can be used simultaneously by unlimited number of people. The data is stored using relational data base systems Oracle, Postgre SQL, IBM DB2 etc.
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