Presentation on theme: "Types of geodatabases File geodatabases—Stored as folders in a file system. Each dataset is held as a file that can scale up to 1 TB in size. The file."— Presentation transcript:
Types of geodatabases File geodatabases—Stored as folders in a file system. Each dataset is held as a file that can scale up to 1 TB in size. The file geodatabase is recommended over personal geodatabases. Personal geodatabases—All datasets are stored within a Microsoft Access data file, which is limited in size to 2 GB. ArcSDE geodatabases—Also known as multiuser geodatabases. Stored in a relational database using Oracle, Microsoft SQL Server, IBM DB2, IBM Informix, or PostgreSQL. These geodatabases require the use of ArcSDE and can be unlimited in size and numbers of users.
The architecture of a Geodatabase Geodatabase storage in relational databases Dataset tables—Each dataset in the geodatabase is stored in one or more tables. The dataset tables work with the system tables to manage data. System tables—The geodatabase system tables keep track of the contents of each geodatabase. They essentially describe the geodatabase schema that specifies all dataset definitions, rules, and relationships. These system tables contain and manage all the metadata required to implement geodatabase properties, data validation rules, and behaviors.
Fundamental datasets in the geodatabase A key geodatabase concept is the dataset. It is the primary mechanism used to organize and use geographic information in ArcGIS. The geodatabase contains three primary dataset types: Feature classes Raster datasets Tables
عناصر قاعدة البيانات الجغرافية
Geodatabase storage in tables and files تخزين قاعدة البيانات الجغرافية في الجداول والملفات
الرسم التوضيحي أدناه يبين جدولين وكيف سجلاتهم يمكن أن تكون ذات صلة ببعضهما البعض باستخدام حقل مشترك
A quick tour of subtypes Subtypes are a subset of features in a feature class, or objects in a table, that share the same attributes. They are used as a method to categorize your data. Subtypes allow you to do the following: Increase the performance of the geodatabase by representing a variety of real- world objects as a subset of features in a given feature class instead of creating new feature classes for each object. For example, the streets in a streets feature class could be categorized into three subtypes: local streets, collector streets, and arterial streets. Set a default value that will automatically apply when creating new features. For example, a local street subtype could be created and defined so that whenever this type of street is added to the feature class, its speed limit attribute is automatically set to 35 miles per hour. Apply coded or ranged domains to features, enabling you to constrain input information to a valid set of values. For example, in a water distribution network, the subtype water mains could have a coded domain for building materials restricting them to be made of cast iron, ductile iron, or copper.
Create connectivity rules between other subtypes and feature classes to maintain the integrity of a network. For example, in a water network, a hydrant can connect to a hydrant lateral but not to a service Create topology rules between other subtypes and feature classes residing in a topology. For example, you could make a requirement that street features have to be connected to other street features at both ends, except in the case of streets belonging to the cul-de-sac or dead-end subtypes. Develop relationship rules between other subtypes, tables, and feature classes.For example, in an electrical network, you could create a relationship rule between subtypes describing that steel poles support class A transformers, while wooden poles support class B transformers. Create customized rules between features using written code.
Working with subtypes Subtypes are records in a table or feature class that have been grouped based on an attribute field. Subtypes are implemented by creating coded values and, therefore, must be associated with fields of the data type short or long integer. These integer values each represent a feature in the subtype. For example, the following codes in a subtype named RoadClass could represent valid classes in a feature class for streets: 0 - Local Streets 1 - Secondary Streets 2 - Main Streets
Subtypes can be created in two ways: Use the context menu in the Catalog tree. Employ geoprocessing using the Subtypes toolset.
Domain There are two different types of attribute domains: – range domains – coded value domains. Each domain has a name, a description, and a specific attribute type to which it can apply.