Establish an entry in the geodatabase
The first step in establishing any database is to design the table to be included. A good design ensures efficient data access. Modelinig Our World discusses the matters to consider to establish a geodatabase.
After you are designed, you can use ArcCatalog to create a database. You can create tables, elements sets, and feature classes in the database. After adding the data to the table and data set, you can add an index on a specific field to increase query efficiency. You can also grant or cancel the right to access tables, feature classes, or elements set for other database users.
Architecture lock
In the multi-user database, more than one user can read and edit the same data at the same time. In order to be able to use the application like ArcMap, the application must assume that the application must be fixed when the data is operated on this architecture. For example, when you increase the feature class from your ArcMap from your geodatabase, it cannot be changed by you or others. When you delete this feature class from ArcMap, and no other user query or edit which feature class, then its mode can be changed.
Shared lock
ArcMap, ArcCatalog or other applications that use ArcObject, automatically get a public lock when editing or querying a feature class or table of a geodatabase. At a moment, any number of public locks of a single feature class or table can be obtained. When using ArcCatalog to change the architecture - Add fields, changing rules, etc., this application is trying to get exclusive locks on the data.
Exclusive lock
A shared lock can only be obtained when there is no other shared lock or exclusive lock on the data. If there is a lock in the feature class or form, ArcCatalog will not build exclusive locks above, and its architecture will not be changed. Once a single lock is obtained, no sharing lock is not obtained, so other users do not utilize ArcMap or ArcCatalog to get data.
Only the owners of the feature or modified table can get exclusive locks, so only the owner can modify the entry in the geodatabase. Some entries in geodatabases - to be discussed in later chapters - such as geometric networks, relationship classes, etc., with special architectural lock behavior. See the independent geodatabase section to get more information.
Personal database
In addition to the scope of the lock is within the database, the architect lock in the personal database is the same characteristic. Once a structure lock is obtained in an entry in your personal geodatabase, this lock is applied to all entries in the geodatabase.
Geodatabase entry
Geodatabases organizes geographic data into a grade data object. These data objects are stored in feature classes, object classes, and feature data sets. Object Class is a table in geodatabase, which does not store space data. A feature class is a collection of elements with the same geometry and the same attribute.
The elements collection is a collection of elements class sharing the same spatial reference. The feature classes of the stored simple elements can be organized inside or outside the elements set. A simple feature class stored outside the elements set is called an independent feature class. The feature class of the storage topology element must be included in the elements set to ensure that these feature classes have the same spatial reference.
ArcCatalog includes tools for establishing an object class (table), feature classes, and elements. Once these items are established in geodatabases, more entries, such as subclasses, simple relationships, compliance with relationships, geometric networks, and topologies can be established.
Spatial reference
When you create a new element collection or independent feature class, you must specify its spatial reference. Space Reference Description Elements (for example, geography, UTM, and State Plane), spatial domain, and accuracy. The spatial domain is allowed by the coordinate X, Y range, M- (metric) value, and Z-Value. Accuracy describes the number of system units for each unit metric. A spatial reference containing accuracy is integrated, and there is a spatial reference for 1000 precision, and the three decimal numbers are stored. Once a spatial reference for a data set or an independent element class is specified, only the coordinate system can be changed, the spatial domain is fixed. The elements of the data set share the same spatial reference. Spatial reference in geographic database design is a very important part of which is a maximum spatial range of data growth in its spatial domain. You have to take care of the appropriate X, Y, M and Z range. For example, if you set the accuracy of 0-1000 for a newly established data set, all Z values in the data collection will not be less than 0, and the z value will be stored as a three decimal number. The same rule applies to the X, Y value, only the m domain is an exception; the elements in the same data set can have different M domains.
The spatial domain of the feature class or elements set cannot be changed. If your geodatabase is required, the range of X, Y, M, or Z value is changed, and the data must be re-imported into the feature class with spatial references that are suitable for new rules.
Pre-defined geographic and projected coordinate systems are set with ArcGIS. You can create a custom coordinate system, or you can import coordinate systems from existing feature classes, elements collection, cover, shapefiles. You can get more information about the spatial reference and spatial domain at ArcSde Administration Guide and Undilling Map Projects.
Space index mesh size
Each feature class has a spatial index with an ArcGIS system automatically generated and maintained. Spatial indexes are used to quickly locate features in a database that meets a certain space search criteria. The space index is based on the parameters provided at the time of element class.
For most database management systems, spatial indexes are a two-dimensional grid system that is full of feature classes, just like you see a positioning grid you have seen on a regular road map.
For most data, as long as a grid size is enough. Because the size of the elements is an important factor for determining an optimized grid size, in order to be a bigger feature as soon as possible, the data that includes different sizes may require additional mesh sizes. Elements can have the maximum three-level grid size, each of the grid sizes must be at least three times the size of the previous grid.
If the spatial index of the element is a grid, it can be changed any time in the existence of the feature class. Get more spatial index grid size information, please see: ArcSde Administration Guide PDF file, and the arcsde configuration and tuning guide for
Field properties (omitted)
