Geographic issues are becoming an increasing part of our daily lives. Regardless of the intensive technical fields such as aerospace, in traditional commercial sectors such as agriculture, energy, transportation, finance, telecommunications, retail, spatial geography is playing an increasingly important role. With the potential of computer-based spatial geographic information, a large number of human and physical force is put into space geographic technology, which also enables people to create a database management system based on geodic data storage. But until 1981, the first commercial geographic information product product products with breakthrough in 1981, people began to truly effectively effectively effectively integrated spatial geography and databases in a single system.
Space geography is booming
---- In fact, spatial geography applications can expand as our imagination. Among them, the B TO B market that people pay attention will be a high growth area. Enterprises can apply this technology in their supply chain to track the location of a particular customer order, or provide targeted management. Many media industries can provide targeted advertisements for customers who meet specific geographical demographic materials. Although Internet technology has nothing to do with geography, people live on the ground, so it will inevitably use spatial geography. In addition, in the United States, the government requires all cellular phones to implement GPS (Global Positioning System) function before October 2001, and spatial geography will also be used in this area. It can lock the caller's location within 400 meters, and the call center that accepts an emergency call can also convert latitude and latitude information into a digital map.
- Another important area for spatial geography applications is client applications. It enables visualization, such as maps or chart display, and you can also implement query and analysis. For example, when the user runs a query operation, the client application writes it and passes it to the database to perform the query process. The database sends the query results back to the client, which can understand how to represent or display data. The client can draw a highway with a red line, draw a secondary route with a gray line, and display other locations such as fire hydrants is displayed. The client can also perform an analysis function, such as calculating the distance between two points. Many client functions can be processed by middleware on the application server during the implementation of the Web-based GIS (geographic information system).
Database management system
---- Spatial Geography is providing help with an industrial and government in a way that cannot be imagined, more and more applications require support for geographic information systems. However, existing available data is more than files in various formats, thereby greatly limiting open access of geodatabase. Although document-based geographic data can be easily shared within a small-scale project group, but data allocation within the enterprise is difficult to handle. This situation often leads to multiple copies of the same geographic data between different working groups of the same enterprise. If there is no highly organized process to manage the repetition of these data, the consistency and integrity of data are difficult to ensure that the reasonable formation of decisions based on the above data is affected. In addition, the mutual binding process of open geographic data and other enterprise core data stored in relational database management systems has also encountered difficulties, and open geographic data access is also limited. This is because the design of the relational database management system module can only support quite limited data types (such as values, characters, and date). In addition, the CAD and graphics processing systems have also developed their own data formats to force any people who want to integrate GIS, CAD and raster graphics data using a variety of data converters.
---- Currently, with the continuous development of technicians, relational databases have become more and more powerful, such as organizational and storage geographic characteristics, providing R-tree indexes and data blade technology, thereby ensuring many tasks. The operation of key applications can be faster and more secure and easier.
---- Organization and storage geographic characteristics
---- In a relational database management system module, the data is stored in a list of rows and columns. The unit consisting of row and column intersection is called a domain, and the data contained in the domain is called value. The line represents a specific event, distance or geographic characteristics, and the column contains the properties of this feature. Attributes have many types, such as dates, text strings, or numbers. Some relational databases, such as Esri Spatial DataBlade Engine (SDE) for Inform, start attempting to use extended SQL data types (as shown in Figure 1), so that geographic characteristics become a numerical type stored in columns. ---- Adding a spatial data type by adding a spatial data type in an object-related database management system to store and manage complex geographic data. Do not change the existing database or affect the current application, but just add a "shape" column to an existing table, providing the software to manage and access the geographic characteristics referenced in the column. With space tables, users can perform data queries and table accumulation as previously, and write queries to return spatial features or use spatial features in the request. The creation and maintenance of spatial objects and space index tables are automated and transparent to users.
---- R-tree index
---- The key to quick access and efficient processing data is index. Although there is a scalable data type, it is more important for effective spatial indexing for very complex space geographic data.
---- Traditional spatial data indexing mode mainly has two types. The first method is to establish a spatial index outside the server and store it in the BNARY LARGE Object, a large binary object. Subsequently, the user can access the index through the middleware and retrieve the BLOB. However, regardless of how the index structure is excellent, since the retrieval portion from the external server is to be included, the retrieval and maintenance of BLOB will result in nature of I / O overhead and concurrent problems, thereby reducing speed and efficiency. The second method is spatial segmentation, so that space is divided into units in accordance with a predetermined mesh or other hierarchical structure (such as a four-dimensional tree). Each unit allocates a number, then each spatial object is associated with the number of its overlapping unit. However, space is not linear sequence, many of the irregularities of many spatial features require complex retrieval, and the necessary checks for many possible errors. It can be seen that this is also a slow speed and low efficiency.
---- In contrast, the R-tree (Region Tree) is a high performance, multi-dimensional access method, which is built into the database core and cooperates directly with the epitaxial data type to properly Manage space geographic data. Different from the standard index, the R-tree is not divided into complete coverage composed of non-overlapping adjacent cells. Instead, it uses the method of data segmentation, so that each object is automatically expressed by the "band" "determined by the spatial shape, which can overlap each other, and do not need to cover the entire space (eg Figure 2 shown in Figure 2, the developer does not have to spend the time pre-understanding the spatial range of the data.
---- Data Blade (DataBlade)
---- Internet is a data propagation. So, how should we extend the company to the Internet, but also don't have to add too much cost? How to transform business data into web content? How do I use existing data to make companies more competitive? For the above problems, in 1996, Informix proposed a Data Blade (DataBlade technology, the technology can integrate any data from any source, providing a stable and flexible Internet application environment.
---- For example, a customer needs to query its current SQL database to search for all residences within 200 meters of some points in the company. If only standard SQL is only used, this seemingly simple query is actually very complicated. . With Informix DataBlade technology, customers can extend the intelligence of the application of the application by increasing the previously mentioned geographic and regional data. What is the result? The number of codes is reduced, and the execution speed is accelerated, and the customer gets the exact rather than the approximate answer. ---- As an extension of server performance, the DataBlade module is integrated at the core part of the engine, integrating traditional data types with rich web content, but there is no sacrifice of traditional relational database management system reliability And scalability. Use a separate DataBlade module or integrate several modules to create a unique information management solution that meets the unique needs of our customers. The DataBlade module is written in a general programming language, which can do the work of general programming, no calls for servers or other data sources. Moreover, the reusable module developed by DataBlade technology can be directly embedded in the database core, as part of the database server, which greatly expands the data support capabilities of the core database server and improves the overall operation performance of the database server.
---- Regardless of how customers develop changes, no matter what kind of information is to manage, and which industry is in which industry is in, using DataBlade technology, it is possible to create a variety of complex, intelligent solutions, and always quickly and cheap. Enable customers to put products in a shorter time, greatly improve customers' competitiveness.
Application development never ends
---- In the past 25 years, people have created a large number of digital space data using GIS, CAD, and graphics processing systems. Now, the following three major development trends have vigorously promote the growing demand for new open space data management methods. First, the need to expand the enterprise's geographic data access is rapidly increased; secondly, the company began to use space positioning to integrate its core business data, and increase space analysis during its business operations; third, for government agencies at all levels It is said that the wide-entered popularity of Internet access has constituted a huge pressure, which prompted to continuously provide public Internet access to existing geographic data.
---- Enterprise will be the biggest beneficiary of spatial geographic technology applications, as they can make full use of advanced visualization and analysis techniques for spatial geography in commercial operations. Analysts pointed out that by adding a space dimension in the business system, companies can develop better decisions. For example, the cellular service provider needs to calculate where the potential user needs to be calculated when expanding the coverage. The application of spatial geography will help answer this question and bring better, intelligent business decisions.
