Once we mention the database, we will naturally think of Oracle. This company was founded in 1977 and was initially a database development company. It is invincible in the development field of Oracle databases. In 1984, relational databases were first transferred to desktop computers.
Then, Oracle's next version, version 5, took the lead in introducing new concepts such as distributed databases and customer/Server structures. Oracle version 6 is the first line lock mode and supports Symmetric Multi-processing computers ...... The latest Oracle8 mainly adds object technology to become a relational-object database system. Currently, ORACLE products cover dozens of large, medium, and minicomputers. Oracle databases have become one of the world's most widely used relational data systems.
Oracle relational database products,Oracle Database has the following excellent features.
1) Compatibility
Oracle products use standard SQL and have been tested by NIST. Compatible with ibm SQL/DS, DB2, INGRES, IDMS/R, etc.
2) portability
Oracle products can run on a wide range of hardware and operating system platforms. It can be installed on 70 or more large, medium, and small computers, and can work in VMS, DOS, UNIX, WINDOWS, and other operating systems.
3) connectability
Can be connected to multiple communication networks and support various protocols, such as TCP/IP, DECnet, and LU6.2 ).
4) High Productivity
A variety of development tools are provided to facilitate further development.
5) Openness
Oracle's good compatibility, portability, connectivity, and high productivity are good open features of Oracle RDBMS. ORACLE products mainly include Oracle database servers, development tools, and connection products.
Database server. The latest version is 8, but 7 is widely used. Version 7 has the following features:
1) multi-process and multi-clue Architecture
Multi-process and multi-clue architecture. Oracle7 includes one or more clue processes, multiple server processes, and multiple background processes. The lead process is responsible for listening to user requests, linking user requests to the Request queue in the memory, and returning the execution results in the response queue to the corresponding user.
The server process processes user requests in the Request queue and links the results to the response queue. The number of threads and threads can be dynamically adjusted based on the current workload. The process structure of Oracle7 can make full use of the multi-processor capability on the Parallel Machine. However, the clues are simulated by processes and scheduled by the operating system, to some extent, this weakens the advantage of low clue overhead.
2) core technologies for improving performance
Oracle7 has improved its core technologies. Its concurrency control mechanism is more refined, including unlimited row-level blocking, no competition query, and the sequence generation mechanism of clues. The shared SQL Cache is added to the shared memory buffer to improve the running efficiency.
3) High Availability
Oracle7 provides multiple mechanisms to ensure high availability and fault tolerance.
4) SQL implementation
Oracle7 SQL complies with ANSI/iso SQL 89 standards. Integrity constraints comply with the ANSI/ISO standards for entity integrity and referential integrity constraints. Provides role-based security.
A role is a set of permissions. With the concept of roles, the security management mechanism can combine some permissions on tables or other database objects and assign them to a role. When needed, you only need to assign this role to one user or a group of users, which can reduce the burden and cost of the security mechanism.
For clusters and MPP parallel computer platforms, Oracle7 provides parallel server options for disk sharing. At the same time, Oracle7 also provides parallel query options for SMP, cluster, and MPP platforms to achieve parallel query, parallel data loading, and other operations.
Oracle7 provides distributed Oracle database functions through distributed options. The distributed option provides multi-site distributed query and multi-site update functions, with location transparency and venue autonomy. It provides a global database name and supports remote process calls.
Development Tools
The Development kits provided by Oracle are Developer/2000, Designer/2000, Discover/2000, and Oracle Office. They cover all aspects from modeling, analysis, design to implementation.
Developer/2000 includes:
Oracle Forms is used to quickly generate complex screen-based applications. It has GUI and multimedia functions and is mainly used to manipulate data and query.
Oracle Reports is a quick report generation tool. It can generate various complex reports and process multimedia information.
Oracle Graphics is used to generate various Graphics applications.
Oracle Books is used to generate online documents.
Designer/2000:
This is the CASE tool provided by Oracle. This tool can help users build, analyze, and design complex systems. It can also help users draw ergraphs, functional hierarchy graphs, data flow graphs, and positional graphs.
Discover/2000:
This is an OLAP tool mainly used to support data warehouse applications. It can mine historical data to find development trends and analyze profile data at different levels, so as to find detailed information about the business.
Oracle Office is applicable to Office automation and can receive and send enterprise-wide messages, schedule, calendar management, directory management, and spelling check.