mongodb relational database

relational databases (MySQL and Oracle) 1. There is a relationship between tables and tables, tables and fields, data and data Advantages: 1. There is a relationship between the data, the data can be deleted and modified to check the time is very convenient 2. Relational databases have transactional operations that ensure data integrity and consistency. Disadvantages: 1. Because the data and data are

A database based on a relational model.A relational database is a collection of data and database objects.Overview: consists of an association between a data table and a data table. A data table is a two-dimensional table that typically consists of rows and columns, each of

Reference: Relational algebra--Division Reference: Database relational algebra expression learning Note: The number of attributes (attribute) of the collection after the join for the normal join:a join B is added to the a,b number of columns (attribute) Natural Join merges all columns with the same name {σ,π,x,∪,-}->{select, Project, Product, union,difference

Label:Relational models can be formally represented as R (u,d,dom,f)R: Relationship NameD: domain of the attributeDOM: Mapping relationships for attributesF: Dependency RelationshipIn the case of Table A (A1, A2,A3):1, A is the relationship name (R).2. If A1 is a number (2) type, then the domain of the attribute is between -99~99, which is the field of the A1 attribute (D).3, if the A2 attribute is the identity, the domain can be "tutor" and "postgraduate", corresponding to the tutor and graduat

MongoDB is a cross-platform, document-oriented database that provides high performance, high availability, and scalability convenience. MongoDB works on the concept of collection and documentation.Database: A database is a collection of physical containers. Each database has

DatabaseType Characteristics Advantages Disadvantages relational databaseSQLite, Oracle, MySQL 1, relational database, refers to the use of a relational model to organizeDatabase of data;2, the most characteristic of relational

Shardsvr = true ReplSet = rs1 Bind_ip = 127.0.0.1, 192.168.10.22 MaxConns = 5000 Fork = true Port = 27011 OplogSize = 1000 Profile = 1 Slowms = 500 Rest = true Directoryperdb = true Journal = true Vi ku2-abr.conf Ogpath =/usr/local/data_mongo/logs/ku2.log Logappend = true Dbpath =/usr/local/data_mongo/ku2_abr Shardsvr = true ReplSet = rs2 Bind_ip = 127.0.0.1, 192.168.10.22 MaxConns = 5000 Fork = true Port = 27013 Vi ku3-zu.conf Logpath =/usr/local/data_mongo/logs/ku3.log Logappend = true

performance. Depending on the structure method and the application situation, the following categories are mainly divided into:Key-value database for high-performance concurrency reading and writing:The main features of the Key-value database, even with extremely high concurrent read and write performance, Redis,tokyo Cabinet,flare is the representative of this class.Document-oriented

administrator. The use command is then used to switch to the target database, and the Db.createuser () command is used to create the user with the role name "ReadWrite".There are two types of common database user roles, read and ReadWrite. As the name implies, the former can only read data cannot be modified, the latter may read and modify.Here is an example:> Use testSwitched to DB test> Db.createuser ({U

Relational database: The principle of relational pattern design1. Paradigm and redundancy of dataFrom 0NF to 1NF, 2NF, 3NF, BCNF, 4NF, 5NF?The process of database design is a split table, the purpose of the split is to reduce the data redundancy.the lower the redundancy of the data, the shorter the transaction duration

invalidated, is a large-grained cache, in the web2.0 for the interaction of frequent applications, Cache performance is not high. NoSQL's cache is record-level and is a fine-grained cache, so NoSQL has a lot of performance at this level. 3. Flexible Data Model NoSQL can store custom data formats at any time without having to create fields in advance for the data to be stored. In the relational database, ad

Tags: and EXT structure Publishing NAT process name Data Model operationsThe SQL (Structured Query Language) database is the primary way to store data over the past 40 years. The late 1990s with the rise of Web applications and open-source databases such as MySQL, PostgreSQL, and SQLite, the explosion of user growth. NoSQL databases have been in existence since the 1960s and have gained more attention until the popularity of databases such as