database system concepts

Label: style Io use strong SP on problem line ApplicationComputer SystemIt consists of four components:Computer hardware,Operating System,System Program,ApplicationsAndUser.HardwareSuch as the central processing unit (CPU), memory (memory), and input/output device (I/O device ).Basic purpose of computer systemsIs to execute user programs and solve user problems more easily. To achieve this goal, a computer

Oracle Cluster Concepts and principles (ii) Overview: write down the original intent and motivation of this document, derived from the Oracle Basic operating Manual of the previous article. The Oracle Basic Operations Manual is a summary of the author's vacation on Oracle's foundational knowledge learning. Then form a summary of the system, a review review, the other is easy to use. This document

Today's small series to share the daily collection and collation of the basic concepts of database, for everyone in the future work is very helpful. 1, Super Key, candidate key, primary key, foreign key Super key: The set of attributes in a relationship that uniquely identifies a tuple is called a hyperlink to a relational pattern. A property can be used as a super key, and multiple attributes can be grou

offline goods (cannot be deleted because of the order, etc., can be migrated). Order module: ..., permanent storage (sub-table, library storage) Shopping Cart module: ... without permanent storage (set archive, cleanup rule) Supplier module: ..., permanent storage Relationship: Logical Design 1. A logical model for translating requirements into databases 2. Show the logical model by the type of ER diagram 3. Independent of the specific DBMS system

The FileSystem API (file system API) simulates a local file system that a network application can navigate to. You can develop applications to read, write, create, and index files in a sandbox virtual file system.The file system API interacts with other related APIs. It is based on the file write API (the files writer API), and the latter is based on the file API

Null in the database means "no input data to (column) variables", that is, NULL in the database can distinguish between "no input data to (column) variables" and "Input data to (column) variables". And the input of the empty string, is here the "have to (column) variable input data" in the case, that is, there is input data, but the input data is an empty string (or The Terminator). In this sense, such as i

This forum article mainly introduces the Oracle database backup strategy related concepts and the use of attention, detailed content please refer to the following First, understand the importance of backup It can be said that from the day the computer system was born, there is the concept of backup, the computer with its powerful speed to deal with the ability t

system Throughput (TPS), user concurrency, performance test concepts and formulasPosted in: DataBase, Linux, UNIX, Windows, Personal diary | Author: a Global person A System Swallow metric elements: The Swallow metric (pressure capability) of a system is closely associat

PS: The following are the main concepts and calculation formulas for performance testing, which are documented below: A System Swallow metric elements: The Swallow metric (pressure capability) of a system is closely associated with the request for CPU consumption, external interfaces, Io, and so on. The higher the CPU consumption of a single reqeust, the slower t

In the same data set, different selection criteria correspond to different output results, and the database is a warehouse that organizes, stores, and manages the data according to the structure. The program or user can use it to make data access and modification, it is the soul of data storage.Data management has undergone 3 stages of human management, file system and