nosql databases vs relational databases

Relational and structured databases, database structuringRelational What is a relational database? The foundation of relational databases is the relational model proposed in 1970. This model consists of three parts:

I. MongoDB Introduction MongoDB (named from "humongous") is a scalable, high-performance, open-source, free-mode, document-oriented database, it combines the advantages of document databases, key-value pairs, and relational databases. Official site: http://www.mongodb.org/,mongodbhighlights: • Document-oriented storage (simple and powerful JSON-like data mode)• D

Tags: nosqlNoSQL databases: Consistency of dataRead consistency Strong consistencyAccess to any node in the cluster at any time, resulting in consistent data results; User consistency for the same user, access to the data during the cluster is consistent;Resolve user consistency: Use sticky sessions to bind sessions to specific nodes for processing;This reduces the performance of the load balancer; Final consistencyThe data synchroniz

toss the bottom platform to build and configuration, simple to complete the installation. This is the Gospel for Hadoop beginners.Pull a little bit more, back in the home to share the installation and use of Dkhadoop, today want to share with you is the database of big Data base content: SQL and NoSQL. To understand these two types of data, it is only necessary to clarify the concepts and how they differ.Both concepts:1, SQL database, refers to the

ObjectRelationalMapping (ORM) is a technology designed to solve the mismatch between object-oriented and relational databases. To put it simply, ORM automatically persists the objects in the program to the relational database by using metadata that describes the ing between objects and databases. In essence, data is co

Exclusive: Microsoft is about to launch pure relational databases for the cloud --> [Csdn latest news in April 30] A few months ago, Microsoft launched the cloud-based SQL data service (SDS), but it was criticized for its lack of strong support for enterprise-level applications. Microsoft is actively promoting a new measure to replace SDS by establishing a pure

and the physical layer of relational data is based on the file form Presentation layer: Table Logical layer: Storage engine Physical layer: File (corresponds to the presentation layer of the file representation) Relational operations Choose Projection Natural connection Cartesian product Set operation Management of

The NoSQL product to be evaluated in this article is Redis. It can be understood as a Key-Value data structure operation. The data is stored in the memory and regularly refreshed to the disk, high read/write efficiency has attracted much attention. Sina Weibo in China uses Redis to store user relationships and count on a large scale. Jieshao According to the official statement, Redis is developed using ansi c and runs on Most POSIX (Linux, * BSD, OS X

In enterprise-level development, relational databases are designed for interface transmission. This article takes oracle database as an example to discuss some design ideas about using databases for intermediate table data transmission during enterprise-level development. You are welcome to leave a message to correct your request. 1. The principle of who controls

1. attributes and domains in the real world, a thing is often described by several features which become attributes ). The value range of each attribute corresponds to a set of values and becomes the domain of the attribute ). Generally, in the relational data model, all domains are limited to atomic data ). For example, integers and strings are atomic data. 1. attributes and domains in the real world, a thing is often described by several features wh

Source: comparison of various nosql databases in http://hi.baidu.com/eastdoor/blog/item/758d0e3eedb5d92471cf6c14.html Cassandra, MongoDB, CouchDB, Redis, Riak, HBaseCouchDBDevelopment language: ErlangMain advantages: data consistency and ease of useLicense: ApacheProtocol: HTTP/RESTApplicable: accumulated, less changed data. Or a large number of versions are required.Example: CRM, CMS systems. multi-site de

I. MongoDB Introduction MongoDB (named from "humongous") is a scalable, high-performance, open-source, free-mode, document-oriented database, it combines the advantages of document databases, key-value pairs, and relational databases. Official site: http://www.mongodb.org/,mongodbhighlights: • Document-oriented storage (simple and powerful JSON-like data mode)• D

, nested loop join, and introduction of inner relation and outer relation two concepts. A relational database defines the definition of a relationship, which can be: A table, an index, and the result of the preceding operation. When connecting two relationships, database connection operations can handle two relationships differently, as defined in this article: The relationship to the left of the join operator is called outer relation; The relationshi

name". Each table should have one or several field values as the identity, ensuring uniqueness of each record. These identities or "keys" can be used to connect information that exists in different tables. For example, you can specify a unique "person number" key value for each person in the people table, and use the same key value in the corresponding field in the Address table. This allows you to associate each person with his or her address by matching the value of the "Person number" field

When saving XML documents in relational databases, you must have encountered many problems due to method reasons, especially for a large number of documents. This articleArticleThe specific problems related to a large number of XML documents will be raised, and then the methods to solve these problems will be provided. Potential problems with a large number of documents What makes an XML document very huge

Document directory I. Data II. The adjacency list Model) 3. Improved forward traversal tree model (the nested set model) An ideal method for storing tree structure data in relational databases In the development of various application systems based on relational databases, we often need to store data in a t

basic relationship R , then property A cannot take a null value. If the attribute(or attribute group) Fis the basic relationshipRthe outer code of it with the basic relationshipSthe main codeKsrelative should(Basic RelationshipsRand theSIt's not necessarily a different relationship.), then forReach tuple in theFThe value must be: Or take a null value(FEach property value is a null value); or equal toSThe primary code value for a tuple in the That is, propertyFIs not the primary property itself