characteristics of dbms

Tags: rollback ISO mysql question notification query interval intro open1. Four characteristics of transactions in the database (ACID) ⑴ atomicity (atomicity) atomicity means that all operations contained in a transaction are either all successful or fail back, and this is the same concept as the previous two blogs about the functionality of the transaction, so that the operation of the transaction must be fully applied to the database if it succeeds

The transaction of the database is a collection of a series of operations (additions and deletions) in the database.In general, the scope of the transaction depends on the business, such as transfer, modification of personal informationTransfer: Transfer $200 from account A to account B Deduction of 200 yuan from a account Add $200 to the B account Modify personal Information: For example, personal information consists of 2 parts, which are stored in two tables "basic information Form

A database transaction is a series of operations performed as a single logical unit of work, either Transaction or none.To become a transaction, a logical unit of work must satisfy the four characteristics (ACID) of the transaction. That is, atomicity (Atomic), consistency (consistent), isolation (insulation), and persistence (duraction).Atomicity (Atomic): A transaction is a complete operation, and the individual steps of a transaction are non-divide

until sees the prompt, can determine the transaction and the correct commit, even if this time the database has the problem, also must have our transaction complete execution, Doing so will cause us to see that the transaction is complete, but the database failed to perform a transaction because of a failure. The above-mentioned four characteristics of the transaction (called acid), now focus on the isolation of the transaction, when multiple thread

a transaction has four characteristics (ACID):atomicity (atomicity)Refers to the entire database transaction is an inseparable unit of work. The entire transaction succeeds only if all operations in the library are successful, and any SQL statement execution fails in the transaction, the SQL statement that has executed successfully must also be revoked, and the state of the database should be returned to the state before the transaction was executed.C

using –noprealloc). The pre-allocation is performed in the background, and each pre-allocated file is populated with 0. This allows MongoDB to always keep extra space and free data files, thus avoiding the congestion caused by the allocation of disk space due to the rapid growth of data. namespaces and disk areasEach database consists of multiple namespaces, each of which stores the corresponding type of data. Each collection in a database has its own namespace, and the index file also has a na

Tags: dir store ons multi-version ima net add to get data httpReference: [1] http://www.cnblogs.com/fjdingsd/p/5273008.html [2] http://blog.csdn.net/fg2006/article/details/6937413Four characteristics of database transactionsIf a database claims to support transactional operations, then the database must have the following four features :⑴ atomicity (atomicity)Atomicity means that all the operations contained in a transaction are either all successful

the transaction and the correct commit, even if this time the database has the problem, also must have our transaction complete execution, Doing so will cause us to see that the transaction is complete, but the database failed to perform a transaction because of a failure. The above-mentioned four characteristics of the transaction (called acid), now focus on the isolation of the transaction, when multiple threads are open transaction operations dat

Reflection characteristics (Attribute)Many people may not yet understand the features, so let's look at what is a feature first. Think about it. If there is a message system, it has a way to send a short message to someone:Title: Author: Author; content: Contents; Receiverid: Recipient IDpublic bool Sendmsg (string title, string author, string content, int receiverid) {Do Send Action}We soon found out that it is very bad to have the parameters listed

Optical Fiber Laser principles and characteristics I. Introduction Fiber Laser (Fiber Laser) is a device that uses glass Fiber reinforced with rare earth elements as the gain medium to produce Laser output. The fiber laser can be developed based on the fiber amplifier. Because the fiber core in the fiber laser is very small, the internal power density of the fiber is high under the pump, in this way, the laser energy level is "inverse of the number

Spring transaction One is misinformation very broadly: one transaction method should not invoke another transaction method, otherwise two transactions will be generated. As a result, developers shackled in the design of transaction methods, fearing that they would step on a mine accidentally.In fact, this is a misunderstanding of the spring transaction propagation mechanism, and spring's support for transaction control is described in the Transactiondefinition class, which has several important

The re module of Python makes many useful improvements to Python regular expressions. After reading this article, I believe you will be able to understand the special characteristics of Python in regular expressions, for example, what is the simplest regular expression. Programmers who need to process text must have a comprehensive and in-depth understanding of regular expressions. This article provides a quick start tutorial for readers who are not f

Special Characteristics of volist tags in thinkphp in ajax operations (recommended), thinkphpvolist Background Implement the volist label in a complex page (including volist) of ThinkPHP to display the return of Jquery query results Knowledge Point The purpose of ajax is to refresh some table data without refreshing the entire page. However, note that the volist tag in the ThinkPHP framework is running on the server, therefore, the thinkPHP tag ca

The market performance of the sea spider Broadband Router is very good, and the demand is also increasing gradually. Here we mainly explain the performance characteristics of the sea spider Broadband Router, in the rapid development of the network era, the Internet cafe industry is evolving in a chain, standardization, and specialization direction from a decentralized and independent business model. Internet-based applications of Internet cafe users h

Angularjs Four characteristics:1. MVC mode:Model: Data, in fact, is the angular variable ($scope. XX, $rootScope. xx);View: Data rendering, html+directive (instruction);Controller: Operation data, is function, data deletion and modification;2, two-way binding:Direction one: Model--->view{model Data}} or Direction two: View--->model3. Dependency Injection:Dependency Injection (Dependency injection, short di) is a design pattern, meaning that an object

Characteristics and analysis of Java languageJava is an object-oriented programming language.(the Java language, represented as a static object-oriented programming language, implements an object-oriented theory that allows programmers to do complex programming in an elegant way of thinking.) ）Java has the characteristics of simplicity, object-oriented, distribution, robustness, security, platform independe

JS Object-oriented features already value types and composite types some properties Empty Object An empty object is also an object, just a variable name with a variable, no object property var o = {}; Parameter passing Value type: Two variables inside and outside the function, two data are not the same Reference type: function inside and outside variables, one data, same address Assign value va

Understanding the three basic characteristics of object-oriented is the basis of understanding the five basic principles of object-oriented.Three major features are: encapsulation, inheritance, polymorphismThe so-called package:That is, the object is encapsulated into an abstract class, and the class can put its own data and methods only trusted class or object operation, to the untrusted information hiding. Encapsulation is one of the object-oriented

At the beginning of the process of learning OC, has been the declaration after the return value of the attribute characteristics do not understand what meaning, today specially found a bit of information, thoroughly understand the meaning of it.The attribute features in OC mainly include Assign,copy,retain, the three main, and the Readonly,readwrite. In addition, Atomic and nonatomic; and Strong,weak.Assign is primarily a simple assignment for the und

Three characteristics of object-oriented design First, the package Good encapsulation reduces coupling, the implementation within the class can be freely modified, and the class has a clear external interface. For example, to build a cat class, and then build a dog class, this is also encapsulated, but there will be a lot of similar code. Ii. inheritance Inheritance occurs because there are too many duplicate code in the objec