Comparison of common database systems-Oracle Database

To bring up the database, the first company to think of, is usually oracle. The company was founded in 1977 and was originally a company specializing in the development of databases. Oracle has a leading position in the database field. In 1984, the relational database was first transferred to the desktop computer. Then, the next version of Oracle,
Version 5, pioneered a new concept of distributed databases, client/server architectures. Oracle's version 6 first-line locking mode and support for Chenduo processing computers ... The newest Oracle8 mainly adds the object technology, becomes the relational-object database system. Oracle is currently one of the most widely used relational data systems in the world, with dozens of models of large, medium and small machines.

Oracle Relational database Products:

Oracle database products have the following excellent features.

(1) Compatibility

Oracle products adopt standard SQL and are tested by the United States National Standards Technology (NIST). Compatible with IBM SQL/DS,DB2,INGRES,IDMS/R.

(2) Portability

Oracle's products can run on a wide range of hardware and operating system platforms. Can be installed in more than 70 different types of large, medium and small machines, can be in VMs, DOS, UNIX, Windows and other operating systems under a variety of operation.

(3) Connectivity

Can be connected with a variety of communication networks, support various protocols (TCP/IP, DECnet, LU6.2, etc.).

(4) High productivity

Provides a variety of development tools, can greatly facilitate the user for further development.

(5) Openness

Oracle's good compatibility, portability, connectivity, and high productivity are open to Oracle RDBMS.

Oracle products mainly include database server, development tools and connectivity products three categories.

Database server

The latest version is 8, but widely used is 7. Version 7 has the following characteristics:

(1) Multi-process, multiple-lead architecture

Multi-process, multiple-cue architecture. Oracle7 includes one to multiple thread processes, multiple server processes, and multiple background processes. The thread process listens for user requests, links user requests to the requested queue of memory, and returns execution results from the answer queue to the appropriate user. The server process is responsible for processing the user requests in the request queue and linking the results to the answer queue. The number of threads and leads can be dynamically adjusted according to the current workload. The ORACLE7 process structure can make full use of the capability of multiprocessor on the parallel machine, but because the clue is simulated by the process, the operating system is dispatched, which weakens the advantage of low thread cost to some extent.

(2) Improving the core technology for improving performance

Oracle7 has improved its core technology. Its concurrency control mechanism is more exquisite, including unrestricted row-level blockade, no competition query, clue sequence number generation mechanism. The shared SQL Cache is added to the shared memory buffer, which improves the running efficiency.

(3) High availability

Oracle7 provides a variety of mechanisms for online backup, online recovery, mirroring, and so on, with high availability and fault tolerance.

(4) SQL implementation

Oracle7 SQL conforms to the ANSI/ISO SQL 89 standard. Integrity constraints conform to ANSI/ISO standard entity integrity and referential integrity constraints. Provides role-based security.

A role is a set of permissions. With the concept of roles, security management mechanisms can be used to combine some of the permissions on a table or other database objects to give them a role. This role is only required to be granted to a user or group of users, which can reduce the burden and cost of the security mechanism.

For cluster and MPP parallel computer platform, ORACLE7 provides parallel server option to implement disk sharing. At the same time, Oracle7 also provides parallel query options for SMP, cluster and MPP platforms to implement parallel query, parallel data loading, and other operations.

ORACLE7 provides distributed database functionality through distributed options. Its distributed options provide multiple site distributed queries and multiple site updates, with location transparency and site autonomy, providing global database names and supporting remote procedure calls.

Development tools

Oracle's Development Toolkit is developer/2000, designer/2000, discover/2000, Oracle office, etc., which covers all aspects of modeling, analysis, design, and implementation.

developer/2000 include:

Oracle forms is used for rapid generation of web-based complex applications with GUI interfaces and multimedia capabilities that are used primarily to manipulate data and queries.

Oracle reports is a quick tool for generating reports. Can generate a variety of complex reports, can also handle multimedia information.

Oracle graphics is used to generate a variety of graphical applications.

Oracle books is used to generate online documentation.

designer/2000:

This is the case tool provided by Oracle. This tool can help users to model, analyze and design complex systems. You can also help users draw ER diagrams, functional layering graphs, data flow diagrams, and square matrices.

discover/2000:

This is an OLAP tool that is primarily used to support data warehouse applications. It can excavate historical data to find development trends, analyze different levels of profile data in order to find out the details about the business.

Oracle Office is designed for office automation and enables enterprise-wide messaging and forwarding, scheduling, calendar management, directory management, and spell checking.