database connection and seamless connection of database noun interpretation

Database connection Pooling Overview

Database connectivity is a critical, limited and expensive resource that is particularly evident in multi-user Web applications. The management of database connections can significantly affect the scalability and robustness of the entire application, affecting the performance metrics of the program. The database connection pool is proposed for this problem.

The database connection pool is responsible for allocating, managing, and freeing the database connection, which allows the application to reuse an existing database connection without having to re-establish a database connection that frees up idle time beyond the maximum idle time to avoid missing the database connection caused by not releasing the database connection. This technique can significantly improve the performance of database operations.

When the database connection pool is initialized, a certain number of database connections are created into the connection pool, which is set by the minimum number of database connections. Regardless of whether or not these database connections are used, the connection pool will always ensure that there are at least as many connections. The maximum number of database connections for the connection pool limits the maximum number of connections that the connection pool can hold, and when the application requests more connections to the connection pool than the maximum number of connections, the requests are added to the wait queue. The minimum number of connections and maximum number of connections for a database connection pool is set to take into account the following factors:

1 The minimum number of connections is the connection pool has been maintained by the database connection, so if the application of the database connection is not used, there will be a large number of database connection resources wasted;

2 The maximum number of connections is the maximum number of connections that can be requested by the connection pool, and if the database connection request exceeds this number, subsequent database connection requests will be added to the wait queue, which will affect the subsequent database operations.

3 If the minimum number of connections to the maximum number of connections is too large, then the first connection request will be profitable, then the connection request exceeding the minimum number of connections is equivalent to establishing a new database connection. However, these database connections that are larger than the minimum number of connections are not released immediately after use, and will be released in the connection pool pending reuse or idle timeout.

Spatial database Seamless Connection

The seamless connection of spatial database is a concept built on the interface of user and spatial database, it is the result of spatial data integration in spatial database, that is to realize transparent access to spatial data according to space, time and topic in user's interface.

Spatial transparency or seamless space is the integration of spatial data set by three dimensions, which forms the integrated information of seamless connection in geo-space.

Time transparency refers to the integration of data in the spatial database according to the time dimension, forming a continuous integrated information in time.

Thematic transparency refers to the integration of data in spatial database by attribute dimension, which forms a continuous integrated information on a certain attribute.

The seamless connection of spatial database includes the following problems in the level of data integration: projection, coordinate system, scale, data precision, thematic logic. The same standard is applied to the spatial data of different projection and coordinate systems on the projection and coordinate systems. On the scale, seamless connection is also the search for a continuous expression of data sets, which is represented in two aspects, namely, the integration between different scales and the same scale data, the natural transition between the same elements of different scales, and the formation of a full scale geospatial data (or some continuous scale). In the same scale, the main is to determine the scale of the level of detail to express a geological process criteria, and then the spatial adjacency of geo-characteristics can be physically or logically connected. The data precision can also be resolved in the form of system ratings or uniform data accuracy to the lowest. The thematic logic is to express different or identical topics in a unified logic.