What is Data Logging?

A data record is a complete set of related information that corresponds to a row of information in a data source. For example, all information about a customer on a customer mailing list is a data record.

In computer science, data refers to the collective name of all media that can be input to a computer and processed by a computer program. It is used for input to an electronic computer for processing and has a certain meaning

According to the meaning of the data warehouse concept, a data warehouse has the following four characteristics:

Data logging is subject oriented

The data organization of the operational database is oriented to transaction processing tasks, and each business system is separated from each other, and the data in the data warehouse is organized according to a certain subject domain. A topic is an abstract concept, which refers to the key aspects that users care about when using a data warehouse to make decisions. A topic is usually related to multiple operational information systems.

Data logging integrated

Transaction-oriented operational databases are usually related to some specific applications, and the databases are independent and often heterogeneous. The data in the data warehouse is obtained through systematic processing, summarization, and arrangement based on the extraction and cleaning of the original decentralized database data. Inconsistencies in the source data must be eliminated to ensure that the information in the data warehouse is about the entire Consistent global information for the business.

Data records are relatively stable

The data in the operational database is usually updated in real time, and the data changes in time as needed. The data of the data warehouse is mainly used for enterprise decision analysis. The data operations involved are mainly data queries. Once a data enters the data warehouse, it will generally be retained for a long time, that is, there are generally a large number of query operations in the data warehouse , But there are few modification and deletion operations, and usually only require regular loading and refreshing.

Data records reflect historical changes

Operational databases are mainly concerned with the data in a certain period of time, and the data in the data warehouse usually contains historical information. The system records the various stages of the enterprise from a certain point in the past (such as when the data warehouse was started) to the current stage Information. Through this information, you can make a quantitative analysis and forecast of the company's development history and future trends.

The construction of an enterprise data warehouse is based on the accumulation of existing enterprise business systems and a large amount of business data. Data warehouse is not a static concept. Only when the information is delivered to the users who need it in time for them to make decisions to improve their business operations can the information work and the information be meaningful. The fundamental task of a data warehouse is to organize and summarize information, and provide it to the corresponding management decision-makers in a timely manner. Therefore, from the industry perspective, data warehouse construction is a project and a process.

A database is a collection of data organized in a secondary model and stored in a secondary storage. This kind of data collection has the following characteristics: it is as non-repeating as possible, and serves multiple applications of a specific organization in an optimal way. Its data structure is independent of the applications that use it. Data is added, deleted, modified, and retrieved by Unified software for management and control. From the history of development, the database is an advanced stage of data management, which was developed by the file management system.

The basic structure of the database is divided into three levels, reflecting three different perspectives on the observation of the database.

(1) Physical data layer. It is the innermost layer of the database and is a collection of data actually stored on the physical storage device. These data are raw data and are objects processed by users. They are composed of bit strings, characters and words processed by the instruction operations described by the internal mode.

(2) Conceptual data layer. It is the middle layer of the database and the overall logical representation of the database. It points out the logical definition of each data and the logical relationship between the data, which is a collection of stored records. It involves the logical relationship of all the objects of the database, not their physical situation, and is a database under the concept of a database administrator.

(3) Logical data layer. It is a database that users see and use, representing a collection of data used by one or some specific users, that is, a collection of logical records.

The connections between different levels of the database are transformed through mapping. The database has the following main features:

(1) Achieve data sharing. Data sharing includes that all users can access the data in the database at the same time. It also includes that users can use the database through interfaces in various ways and provide data sharing.

(2) Reduce data redundancy. Compared with the file system, the database realizes data sharing, which prevents users from creating application files. A large amount of duplicate data is reduced, data redundancy is reduced, and data consistency is maintained.

(3) Independence of data. The independence of data includes the independence of the logical structure of the database and the application in the database, as well as the change of the physical structure of the data without affecting the logical structure of the data.

(4) Centralized control of data. In the file management method, the data is in a decentralized state, and different users or the same user have no relationship between their files in different processes. The database can be used for centralized control and management of the data, and the data model represents the organization of various data and the relationships between the data.

(5) Data consistency and maintainability to ensure data security and reliability. It mainly includes: security control: to prevent data loss, erroneous update and unauthorized use; integrity control: to ensure the correctness, validity and compatibility of data; concurrency control: to allow the same time period to allow Data can be accessed in multiple ways, and it can prevent abnormal interaction between users. Fault detection and recovery: A set of methods is provided by the database management system to detect and repair faults in time to prevent data from being destroyed.