Principle

In SuperMap SDX+, spatial objects are classified based on a certain property field of the dataset or a given range (the length and width of the map sheet), and managed through an index to improve query and retrieval speed. The figure below shows a tiled composite map of China's municipal administrative boundaries. After creating a mapsheet index for the given range, the scene of h4708 is displayed. The mapsheet index is particularly advantageous for displaying and querying massive data (i.e., data with over one million objects). After building a mapsheet index, only the map sheet(s) you need to view are displayed, greatly reducing display time.

Figure: Schematic Diagram of Mapsheet Index

Additionally, the mapsheet index can be cached locally (in binary file form), further improving query and retrieval speed. The file is an intelligent distributed storage solution provided by SuperMap SDX+ to balance network and server loads and enhance overall application performance. After enabling the file option, when the application accesses data stored in the spatial database, it first checks whether the local database already has the latest version of the corresponding data. If not, or if the data is not the latest version, it reads the data from the server and updates the local data, so that the next time it accesses the local data directly. If the local version is already the latest, the application reads the local data directly without requesting data from the server via the network, thereby completing display or analysis functions. This solution can significantly reduce database server load and network load, thus improving the overall performance of the application.

Applicable Scenarios

For datasets generated by merging data stored in standard scale tiles (e.g., 1:250,000 data, 1:100,000 data, 1:50,000 data) into a database, the mapsheet index provides excellent performance, delivering very good query efficiency. When used in combination with SuperMap options, it can achieve faster map browsing speed.

Tip:

• The algorithm for building a mapsheet index was significantly improved in version 5.3. Depending on the data volume, index creation time can be reduced by 4 to 10 times. For datasets with a large number of records (more than 50,000), it is recommended to use version 5.3 or later to create the mapsheet index.
• Currently, the mapsheet index only supports point, line, polygon, text, and CAD datasets in database datasources.
• The engine types that support building a mapsheet index include: SQLPlus, OraclePlus, KingBase, MySQL.