hadoop relational database

(1nf) means that each column in the database table is an inseparable basic data item, that is, an attribute in the entity cannot have multiple values or duplicate attributes. In any relational database, the first paradigm (1nf) is the basic requirement for the relational model. databases that do not meet the first par

information data storage, and improves the speed of data query and image acquisition. This article describes DICOM query/retriev. Based on the service class, the query/retrieve information model is analyzed, and the information model is implemented using Relational Database Service (RDS) ms SQL Server2000, finally, the offis DCMTK is used to verify the feasibility and correctness of Using

database. The object in the file, easy to implement, simple to operate, there are many class libraries have implemented this function, but the file storage method is difficult to express the relationship between the objects, performance is also insufficient, difficult to meet the requirements of large systems. The ideal choice is object-oriented database, but the object-oriented

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

The next step is to explain each level of the paradigm, firstThe first paradigm (1NF). Conforms to the 1NF relationship (you can understand it as a data table.) The difference between "relationship" and "relationship pattern" is similar to the difference between "class" and "Object" in object-oriented programming. "Relationship" is an example of "relational pattern", you can understand "relationship" as a table with data, and "

Greenplum + Hadoop learning notes-11-distributed database storage and query processing, hadoop-11- 3. 1. Distributed Storage Greenplum is a distributed database system. Therefore, all its business data is physically stored in the database of all Segment instances in the clu

stored procedure Store function trigger Event SchedulerConstraints:Domain constraints: Data type constraintsFOREIGN KEY constraints: referential integrity constraintsPRIMARY KEY constraint: A field can uniquely represent the entity to which this field belongs, and is not allowed to be emptyA table can have only one primary keyUnique key constraint: A field in each row is not allowed to have the same value, can be emptyA table can have more than one unique keyCheck constraint: Age:intConstraintT

Object-oriented is developed from the basic Principles of software engineering (such as coupling, aggregation and encapsulation), and the relational database is developed from the mathematical theory, the two sets of theories have distinct differences, and Java is a completely object-oriented language, and this conflict is becoming more and more obvious. For the current information system of Java EE, the pr

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

Nowadays, the BigTable (column family) database is used more and more widely, and the function is very powerful. But many people still regard it as a relational database in use, with the original relational database thinking to build tables, storage, query. This article take

Tags: key codis decision IMG Native transaction mechanism mongod contrast algorithmThe famous open source distributed cache service Codis's author, Pingcap co-founder CTO, Senior Infrastructure engineer Huangdongxu, specializes in the design and implementation of distributed storage systems, the technology of open source fanatics, the great deity level figures. Even today, when the Internet is so prosperous, in the vague and uncertain boundaries of the data