mongodb relational database

Question:Preliminary understanding of multidimensional database and relational database are table storage, but in the cube is called the fact table, the dimension table, do the analysis of the relational database can do it? (the book says that the multidimensional

the projection operation, because once a particular column is selected, duplicate rows may be generated, and the duplicate rows must be eliminated3, connection.A connection that is a connection condition by one of the attributes in one relationship that is equal to a property of another relationship.Logical Database DesignTransforming entities and relationships into relational patternsFunction-dependentLos

wp_term_relationships classification relationship table, as shown in (this figure is from the Northwestern University WordPress source code interpretation team: Wp_term_relationships classification relational table -- WordPress Database The association between the wp_term_relationships classification table and other data tables: The wp_term_relationships classification relation table is associated with

we can use to analogy the document into each row of data in a relational database. Multiple keys and their associated values are placed together in an orderly manner as documents. Bson stores data in MongoDB using a class JSON. Bson data can be understood to add some data types that are not in JSON, based on JSON. If we would have JSON, then we would have master

apply it directly. I took this book in October this year, so I should practice it first. The previous video from instructor Yan jianling focuses on the specific operations in the database, there is not much to do with the necessary steps in database design, that is, the conversion from the conceptual model to the logical model. Enter the subject: Background: Data System survival The entire period from plan

Relational data StructuresEntities, relationships between entities are relational representations, and the logical structure of the user's angle is the two-dimensional tableRelationship: A subset of Cartesian productRelationship Operations Collection Traditional set operation: And, intersection, difference, Cartesian product dedicated relational operati

"　　8.getrange key 0 4 #---------------------Gets the value at the specified range position127.0.0.1:6379[2]> set name ' 12345678 ' ok127.0.0.1:6379[2]> getrange name 1 3 "234"　　9.mget key 1 Key 2 .... #---------------------the value of the bulk fetch key127.0.0.1:6379[2]> mget We er rt1) "ew" 2) "ER" 3) "RT"10.INCR Key #---------------------do self-add 1 for the specified key value127.0.0.1:6379[2]> Set ID 12ok127.0.0.1:6379[2]> incr ID (integer) 13127.0.0.1:6379[2]> incr ID (integer) 14127.0.0.

Label:First normal: There are no duplicate columns.Second paradigm: To have a unique identity.The third paradigm: not dependent on non-primary keys.Implemented the third paradigm, which shows that the first and second paradigm have been realized.does not conform to the third paradigm, the database table will have a pruning exception, and generate a large amount of redundant data.For a better understanding of the meaning of the three paradigms, please

Label:Requirements: Export the TBLs table from the hive database to HDFs;$SQOOP 2_home/bin/sqoop. SHSqoop:Theset server--host hadoop000--port 12000--webapp sqoopServer is set SuccessfullyCreate connection:Sqoop the>Create connection--cid 1Creating Connection forConnector withID 1Please fill following values to create new connectionObjectName: tbls_import_demoConnection configurationjdbc Driver Class: com.mysql.jdbc.DriverJDBC Connection String: jdbc:m

Tags: des blog http using strong dataI believe that the development experience of friends have encountered such a demand. Suppose you are developing a comment function for a news site, and readers can comment on the original text or even reply to each other.This need is not simple, mutual reply will lead to an infinite number of branches, an infinite number of ancestor-descendant relationships. This is a typical recursive relational data.For this prob

Because of the needs of the work, need to transfer the data in HDFs to the relational database to become the corresponding table, on the Internet to find the relevant data for a long, found that different statements, the following is my own test process: To use Sqoop to achieve this need, first understand what Sqoop is. Sqoop is a tool used to transfer data from Hadoop and

I. First paradigmIn any relational database, the first paradigm (1NF) is the basic requirement for relational schemas, and a database that does not meet the first normal form (1NF) is not a relational database. The so-called First

The application of relational database system began in the 1980s, so far it has become the most popular database system. In a relational database system, the data in its database is logically organized based on the relationship. A

Tags: Big Data eraSqoop as a Hadoop The bridge between the traditional database and the data import and export plays an important role. by expounding the basic grammar and function of Sqoop, the paper deeply decrypts the function and value of Sqoop. First, what is Apache Sqoop?Clouderadeveloped byApacheOpen Source project, isSql-to-hadoopthe abbreviation. Mainly used inHadoop (Hive)with the traditional database