Welcome to my “Database management software definition.”
In the past, DBMS of the network type data model proposed by CODASYL, DBMS of the hierarchical data model, DBMS of the card type data model (so-called simple database software) etc. were widely used in the initial non-powerful personal computer , But in recent years a relational database management system (RDBMS) that deals with relational models (relational data models) is mainstream.
In addition, the relational database management system includes an object-relational database (ORDBMS) that allows users to extend their own data types and functions, an object database (ODBMS) that has high affinity with object-oriented programming languages, and XML The adopted XML database (XML DB) and the like have been developed and widespread use.
Although the DBMS of the network type data model and the DBMS of the hierarchical data model had been widespread from the lightweight nature of the implementation early, the application software, the logical structure of the data, the physical structure of the data are tightly coupled, It has the drawback of lacking flexibility. The optimization methodology also depends on the competence of programmers who make queries (search questions), which has also contributed to lowering the efficiency of application development.
The greatest achievement of the relational model lies in realizing logical data independence and physical data independence by dividing the application, data logical structure, and data physical structure into three hierarchies (three hierarchical architecture).
Today, the following databases are widely used. See also NoSQL for the last two.
Relational Database, Object-Relationship Database - Schema is solid and transactions are available
Object database
Document Oriented Database - schema-less one using XML database or JSON
Key value store, column-oriented database - Column-oriented one whose value is a hash table
In addition, the relational database management system includes an object-relational database (ORDBMS) that allows users to extend their own data types and functions, an object database (ODBMS) that has high affinity with object-oriented programming languages, and XML The adopted XML database (XML DB) and the like have been developed and widespread use.
Although the DBMS of the network type data model and the DBMS of the hierarchical data model had been widespread from the lightweight nature of the implementation early, the application software, the logical structure of the data, the physical structure of the data are tightly coupled, It has the drawback of lacking flexibility. The optimization methodology also depends on the competence of programmers who make queries (search questions), which has also contributed to lowering the efficiency of application development.
The greatest achievement of the relational model lies in realizing logical data independence and physical data independence by dividing the application, data logical structure, and data physical structure into three hierarchies (three hierarchical architecture).
Today, the following databases are widely used. See also NoSQL for the last two.
Relational Database, Object-Relationship Database - Schema is solid and transactions are available
Object database
Document Oriented Database - schema-less one using XML database or JSON
Key value store, column-oriented database - Column-oriented one whose value is a hash table
Database language
The database language is a language for conveying various instructions to the DBMS. Conceptually, it consists of constituent elements of data definition language (DDL), data manipulation language (DML), data control language (DCL). The Data Definition Language (DDL) defines the structure of the database. The data manipulation language (DML) performs operations such as retrieval and update to the database. Data control language (DCL) controls access to data. DBMS has a database language based on its database model. For example, most of the systems which are regarded as relational database management systems (RDBMS) are equipped with relational database language SQL.
Physical data independence
When changing the storage device storing the database, there is no need to change (or reduce the effort to change) the method of accessing the DBMS accordingly. The DBMS can hide the change of the storage device to some extent to the user or the application software accessing the DBMS.
Logical data independence
Several types of DBMSs support logical data independence. For example, you can use views in RDBMS.
Data integrity
Prevent incorrect data from being registered and being updated to illegal data. For example, the RDBMS has functions such as domain, data type, uniqueness constraint, referential integrity constraint, general constraint, and trigger.
Transaction processing
Perform transaction processing based on ACID characteristics. Even when multiple users refer to and update the same data at the same time, they perform processing normally without inconsistency.
Security
Many DBMSs provide arbitrary access control or mandatory access control regarding security (security), and some DBMSs also provide data encryption functions. Many DBMS adopt arbitrary access control. In the data encryption function, as a countermeasure against illegal data accesses bypassing the DBMS, data managed and transmitted/received by the DBMS is encrypted.
Disaster recovery
It recovers from transaction failure, system failure, and failure of the storage medium.
Optimisation
In the DBMS adopting a high-level database model, data processing requests described in a high-level database language are optimized for low-level procedures and executed.
Distributed database
The distributed database is a technology that uses multiple computers connected by a network and coordinates the process of DBMS on each computer and realizes one DBMS virtually as a whole. Since multiple computers are used, availability and processing performance can be improved. The database of the client/server can be regarded as a simple and special form of the distributed database.
The database language is a language for conveying various instructions to the DBMS. Conceptually, it consists of constituent elements of data definition language (DDL), data manipulation language (DML), data control language (DCL). The Data Definition Language (DDL) defines the structure of the database. The data manipulation language (DML) performs operations such as retrieval and update to the database. Data control language (DCL) controls access to data. DBMS has a database language based on its database model. For example, most of the systems which are regarded as relational database management systems (RDBMS) are equipped with relational database language SQL.
Physical data independence
When changing the storage device storing the database, there is no need to change (or reduce the effort to change) the method of accessing the DBMS accordingly. The DBMS can hide the change of the storage device to some extent to the user or the application software accessing the DBMS.
Logical data independence
Several types of DBMSs support logical data independence. For example, you can use views in RDBMS.
Data integrity
Prevent incorrect data from being registered and being updated to illegal data. For example, the RDBMS has functions such as domain, data type, uniqueness constraint, referential integrity constraint, general constraint, and trigger.
Transaction processing
Perform transaction processing based on ACID characteristics. Even when multiple users refer to and update the same data at the same time, they perform processing normally without inconsistency.
Security
Many DBMSs provide arbitrary access control or mandatory access control regarding security (security), and some DBMSs also provide data encryption functions. Many DBMS adopt arbitrary access control. In the data encryption function, as a countermeasure against illegal data accesses bypassing the DBMS, data managed and transmitted/received by the DBMS is encrypted.
Disaster recovery
It recovers from transaction failure, system failure, and failure of the storage medium.
Optimisation
In the DBMS adopting a high-level database model, data processing requests described in a high-level database language are optimized for low-level procedures and executed.
Distributed database
The distributed database is a technology that uses multiple computers connected by a network and coordinates the process of DBMS on each computer and realizes one DBMS virtually as a whole. Since multiple computers are used, availability and processing performance can be improved. The database of the client/server can be regarded as a simple and special form of the distributed database.
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