Hierarchical Manager Solution for Oracle Data Warehouse

Abstract: This article describes the principles, steps, and restrictions of the hierarchical manager, and combines it with Oracle Data warehouse to achieve effective storage, management, and quick browsing of large-scale data.

 

Quick viewing of metadata in the keyword layered Manager

　　

Preface

 

The 21st century is the century of information, and the competition of comprehensive national strength is, to a large extent, the competition of information utilization. In recent years, with the proposal and implementation of the "digital earth" and "Digital Land" strategies, massive data in the field of geology is growing rapidly, and data storage, analysis, management, and processing become increasingly complex. With the maturity of Oracle technology, especially the emergence of Oracle Spatial after version 8.15, Data Warehouses have unparalleled advantages in massive data storage, analysis, and expression. At the same time, due to the huge amount of information, the traditional data storage and display methods are insufficient for large-scale data quick browsing. In this way, it is necessary to change the storage mode of spatial data and load the required spatial data, avoid repeated loading and uninstallation of unnecessary data.

 

Layered Manager

 

1. Hierarchical Manager architecture

 

The layered manager is a key part for quick browsing of large-scale data. It controls the layer-by-layer refinement of the table structure and metadata definition and assignment, and defines the key information in the component table, the spatial data sources, data mining rules, layer loading ranges, and graphic editing, output, and storage are provided. The layered Manager consists of two parts:

 

A) a group of spatial data tables stored in the Oracle data warehouse are used to refine each detail layer in layers. These tables are called component tables;

 

B) an empty table that contains the structure definition of the table and the special metadata used to describe the component table. This table is called a layer-by-layer refined table. Any layer-by-layer refinement application requires layer-by-layer refinement of tables, from which you can understand the layer-by-layer keyword descriptions of layers in layer-by-layer refinement, and the hierarchical association between them. When layering, the layering manager acts as a part of the program and determines the layer and Keywords of the sub-Picture Elements to be added, so as to determine the information of the elements to be added and deleted in layer-by-layer refining layers.

 

A layer-by-layer refined layer is a special map layer. It is a blank layer with its own table structure and uses metadata to specify rules and restrictions for all layers to be loaded, the displayed map information is extracted from other tables or databases according to the rules specified by metadata. When a layer-by-layer refinement layer is displayed in the map, the layer manager creates a temporary table and copies the elements in the component table to the temporary table. The elements displayed in layer-by-layer refinement layers are actually copies of elements in the component table. In this way, you can flexibly load the required information on the layer. When the application ends, the temporary table is discarded. To save useful topic chart information, you can save the extracted layers. At this time, if you view the layer information, the layer-by-layer refinement layer will still be a single layer.

 

A layer-by-layer table refinement requirement is the core part of the organization of the layered manager. It defines metadata keywords and three standard columns: keywords, layers, and labels. It also has its own set of syntax:

 

(1) The begin_metadata keyword marks the beginning of the metadata section in the table layer-by-layer refinement.

 

(2) Each row of metadata contains two elements: keywords and values. All keywords and values are enclosed in double quotation marks.

 

(3) A layer-by-layer refined table must contain the "IsDrilldown keyword. The value of this keyword must be True.

 

(4) Each keyword starts with "" (backslash.

 

(5) Metadata keywords can be nested in hierarchies. Each layer in the hierarchy is marked with a backslash.

 

(6) Metadata includes the "DDMap" ComponentMaps "keyword hierarchy. Specify four metadata keywords for each component table in this hierarchy.

 

The layered manager's layered schematic 1 shows that the layered Manager consists of two parts: component table and layer-by-layer refined table, the layer manager extracts data from the Oracle Data Warehouse by means of Data Mining according to system requirements to form a layer in the component table, and then determines the name and part of the layer to be loaded, and load it to a layer-by-layer table. If this is the first time a table is loaded, the layer-by-layer refinement table is a blank layer. During the loading process, the layer-by-layer refinement table continuously adds and deletes the metadata information, in this way, some information in each component table is displayed in the layers shown in the layer-by-layer refined table. In this way, output the required layer and edit it. Because layer-by-layer data refinement in the table is a copy of the component table, you need to save the edited layer to form a topic chart.

 

 

 

 

 

The layer manager first forms a blank layer, uses the layer manager to extract data from the Oracle Data Warehouse with data mining tools, and forms a level-1 layer according to the metadata rules of the layer manager. In this layer, by responding to the event, we can determine the name of the layer that loads the second-level layer and the loaded part of the layer. The layer-3 and layer-4 data are loaded accordingly, and various topic diagrams are formed at the same time. Of course, the implementation of the hierarchical manager function is achieved through GIS components (MapX, MO, AO, etc.) and programming languages (VB, VC, Delphi, etc.

 

2. Hierarchical manager development steps

 

The layered Manager application requires many settings and preparation. The main steps are as follows:

(1) obtain the data of each table to be used when layers are refined layer by layer.

(2) create a new empty layer-by-layer table (. tab file) that contains special columns and special metadata ). The metadata specifies a layer name for each component table and identifies the important column identification column and the title column in the component table.

(3) add layer-by-layer refined tables to the map. For example, add a layer-by-layer refined table to your Geoset, or add a layer-by-layer refined table to the map using the encoding method.

(4) add user interface elements to the application to respond to layer-by-layer events.

(5) Add code to respond to the user's use of layer-by-layer refinement tools (that is, write a layer-by-layer manager ).

(6) The code needs to detect the selected elements of the user, determine the subgraphs to be added and the elements to be deleted, and call the application program to implement stratified or aggregated map elements.

Instance analysis

 

Because remote sensing has a huge impact on data volumes, it is very difficult to store, manage, analyze, and display data in some useful graphs. This requires the use of relational databases to store data. To obtain useful layer information, reduce loading time, and improve Editing efficiency, You need to display the image hierarchically, that is, the layer manager technology described above. This article uses VB as the programming language and MapX as the GIS component for secondary development to achieve hierarchical management technology.

 

1. Build a hierarchical Manager

 

Build a layer-by-layer table with the following table structures:

 

Definition Table

 

Type Native Charset "WindowsLatin1"

 

Fields 3

 

Key Char (32 );

 

Level Char (32 );

 

Label Char (32 );

 

The metadata keyword and corresponding value are:

 

Begin_metadata

 

"" IsDrilldown "=" TRUE"

 

"" DDMap "ComponentMaps" One "File" = "Tab_YNP.TAB"

 

"" DDMap "ComponentMaps" One "LevelID" = "Tab_YNP"

 

"" DDMap "ComponentMaps" One "FeatureIDCol" = "3"

 

"" DDMap "ComponentMaps" One "FeatureCaptionCol" = "1"

 

... (The keywords and values of other component layers are the same)

 

"" DDMap "HierarchyManager" IsDLL "=" TRUE"

 

"" DDMap "HierarchyManager" ID "=" SomeDLL. dll"

 

"" DDMap "HierarchyManager" InitialLevel "=" Tab_YNP"

 

End_metadata

 

2. Implementation of hierarchical Manager

 

The CreateCustomTool method is used to implement layer-by-layer refinement tools, which are defined as: Map1.CreateCustomTool customDrilldownExpandTool, miToolTypePoint, miDrilldownExpandCursor, midrilldowndowncontractcursor

Each time you use a custom layer-by-layer refinement tool, the ToolUsed event is triggered. During the ToolUsed event, you need to execute code that generates layer-by-layer refined behavior. This process consists of four steps:

(1) Use SelectByPoint or SearchAtPoint to determine the map elements clicked by the user.

(2) determine the subgraph metaset that should replace the elements clicked by the user. For example, you can use one or more nested Case statements to determine which subgraph elements Replace the selected parent element.

(3) extract spatial data. Based on the preceding conditions, extract information from the data warehouse using the SQL language, for example, select goloc form YN. Tab_HQ_KC where Prix = 68

(4) Call the DrilldownAddFeatures method to add the subgraph element to the map.

(5) Call the DrilldownRemoveFeatures method to delete the parent element (the element clicked by the user) from the map ).

(6) edit the display layer and save the editing result.

 

3. Result Analysis

 

From the instance results, we can see that the Oracle Data Warehouse can conveniently store, analyze, manage, and output space data, and the application of data mining technology can flexibly access data, without loading all the data in the entire data table, the application of the layered Manager enables quick browsing of spatial data in a large range and partial superposition of different theme layers. in practical applications, it is very convenient.

 

Conclusion

 

Efficient use of existing massive data is one of the challenges currently. Oracle data warehouse is a technology dedicated to the Management and Application of massive data. It has obvious advantages in object-relational databases, powerful DBMS, and visual search. The theory of the data warehouse has been continuously improved in this year's application. This paper combines the theory with the actual application in the storage, analysis and expression layers of the data warehouse, combined with the secondary development of hierarchical management GIS, a hierarchical management system based on Oracle Data Warehouse is developed, which combines the advantages of data warehouse and hierarchical management, it has made some useful attempts in the space data application.