relational database vs nosql

. The Minimum Redundancy must be achieved on the premise that the decomposed database can express all information of the original database. Its fundamental goal is to save storage space, avoid data inconsistency, improve the efficiency of relational operations, and meet application requirements. In fact, it is not necessarily required that all models reach bcnf.

After the concept of database was put forward, several data models appeared successively. There are three kinds of basic data models: Hierarchical model system, network model system, and relational model system. The relationship model proposed in the late 60 has the characteristics of simple and flexible data structure, easy to understand and strong mathematical foundation, and it has been popular since the

connection, which requires that the property names in the two relationships be compared, and that duplicate columns are dropped in the result Some tuples in the relationship R do not exist in the corresponding S, so it is possible to be discarded and become suspended tuples (Dangline tuple) The suspension tuple is reserved and null is filled in as an outer join. Leave left and right respectively left connected rightExcept operationsR/S ={tr[x] | Tr belongs to R and Πy (S) belongs to YX}

This paper mainly introduces the theoretical basis of relational database design which is closely related to the establishment of relational model (i.e. relational table structure), which is the basic knowledge of relational paradigm. The paradigm theory provides a theoretic

Recently, a large number of new relational databases have sprung up in clouds outside the cloud. One of the key messages released here is: "If you want to get rich and on-demand scalability, you need a database that is not relational." ” If this is true, then is this not a sign that the once powerful relational

Relational Database Terms and Definitions 1. Key: it is an important concept in a relational model. It is used to identify one or more columns of a row in a relational model. 2. Candidate Key: it is an attribute set that uniquely identifies a row in a table and does not contain any redundant attributes. That is, i

Infi-chu:http://www.cnblogs.com/Infi-chu/relational databaseRelational database is a database based on relational model, and the relational model is saved by a two-dimensional table, so the storage of relational

In terms of creating, communicating, accessing content, sharing information, and buying products, the rapid expansion of a new generation of internet-based services, such as e-mail, blogs, social media, search, and E-commerce, has actually redefined the behavior and trends of WEB users. As the number of these systems continues to grow, IT professionals are witnessing the scaling up of data and data consumed, and growing scalability requirements and new functional requirements pose new challenges

Tags: delete a prim number href work otherwise HTTP keywordBasic concepts: keywords, primary keywords, candidate keywords, non-keywords If the value of a field or multiple fields uniquely identifies a record, the field or field group is called a keyword .If a keyword is used to identify the uniqueness of each record and is associated with other table implementations, it is called the primary key (primary key, primary key), or the main code .A keyword other than the primary keyword is called a ca

Tags: databaseThe database system is one kind of software, the database system naturally also has his own life cycle--the lifetime. Its lifetime begins with planning, until it is uninstalled. Its intermediate process is very complex, in order to realize the user's idea, the database personnel will abstract the real life data, then in the classification and the op

Dotnet core uses MongoDB for high-performance Nosql database operations. mongodbnosql I haven't written a Blog for a long time. I watched the open-source Java Community drool every day, and I was so confused that I finally waited for the official release of dotnet core in March, Looking at the dotnet community, it is also a thriving phenomenon. I don't want to bind Windows. I believe that the spring of dotn

This section describes the theory of Relational Database Design Based on relational algebra. Function dependency is the basic part, and various paradigms are introduced in the constraints of Pattern Design and their coping problems. 3.1 function dependency The relationship design theory allows people to test and improve a design based on a few simple principles.

Label:Original address: http://www.jdon.com/39240The article summarizes the following points:1. Write frequently, rarely read statistics, such as CTR, should use memory-based in-memory Key/value storage database such as Redis, or update-in-place text storage such as MongoDB.2. Big data (such as weather data Business analysis data) can use distributed database systems such as Hadoop.3. Binary data (such as M

Tags: differentiating CTC identity sel paradigm Problem _id Third paradigm RelationshipThe sixth chapter of relational data theory This chapter explains the relationship normalization theory in detail, which is not only the important theoretical foundation of relational database but also the powerful tool of database d

An important part of designing a relational database is dividing the data elements into related tables. Once you're ready to start working with the data, you can rely on relationships between tables to aggregate the data in a meaningful way. For example, unless you know which customer placed a particular order, the order information is useless. So far, you may have realized that you did not store customer a

Introduction to 1.mongodbMongoDB (http://www.mongodb.org/) is a high performance, open source (the generation of Earthquake army Daniel is studying MongoDB source code, we can go to see http://www.cnblogs.com/daizhj/), Mode Freedom ( Schema-free) is a document-based database that can be used in many scenarios to replace traditional relational databases or key/value (Key-value) storage methods. MongoDB uses

A distributed model of a NoSQL database single serverWhen a server is fully competent to work, there is no need to consider the distribution, so the deployment is simple, maintenance is much more convenient;Shard FeaturesThe various parts of the data are stored in different servers in the cluster;For example, according to the letter: the key values starting with A-G are stored on the first server, with the

Index Understand the related tables. FOREIGN key JOIN and maintain referential integrity For some suggestions on joins, subquery VS. Linked table Query I found that there is a tutorial in the MySQL documentation, but the concept does not seem to mention, just tell you how (statement), did not tell you the cause and consequences (principle). Want to see a book with vivid explanations, such as the one that will give the various joins the VN diagram, and do not know how to fin

1.1.1 What is relational dataRelational data is data that is represented by a relational mathematical model. The relational mathematical model describes the data in the form of a two-dimensional table, as shown in tables 1.1 and 1.2.1.1.2 What is a relational database1. What is the main code (primary key)A combination

Nosql is a hot topic recently. It can be seen in high-performance and high-concurrency systems. For example, memcached and MongoDB, memcached only supports column-store, And MongoDB does not support transactions. Most importantly, these require server support. In some embedded systems, the hardware environment is overwhelmed by the old bull. At a friend's suggestion, I tried to use db4o and found that such a good