star schema vs snowflake schema

Oracle Star Schema analysis Star conversion is a very powerful optimization technology, which is implemented by implicit rewriting of the original SQL statement, it can greatly reduce I/O. end users do not need to know any details about star conversion. The database optimizer performs

1. The classic Star Schema1) dimension tablesDimension attribute/described attributes (non-dimension attributes)Answer to "What/whe/WHO /..."Described attributes correspond to master Data .2) fact tableAnswer to "How much/how many", focus on "amount/quantity ..."Link to dimension table by a unique keyFrom OLTP perspective, fact table 3) star schema can answer the

structure does not need to consider many regularization factors, design and implementation are relatively simple. Snowflake model because of redundancy, some statistics need to be linked to the table to produce, so the efficiency does not necessarily have a star model high. Regularization is also a complex process, the corresponding database structure design, data ETL, as well as the maintenance of the lat

implementation are relatively simple. Snowflake model because of redundancy, some statistics need to be linked to the table to produce, so the efficiency does not necessarily have a star model high. Regularization is also a complex process, the corresponding database structure design, data ETL, as well as the maintenance of the latter are more complex. Therefore, in the premise of the redundancy acceptable

combine a variety of queries. Conclusion: 1> of non-formal;2> each dimension in a cube is connected to the fact table (via primary key and foreign key);3> does not exist in the gradient dimension;4> has redundant data;5> query efficiency may be relatively high;6> does not need to consider the regularization factor too much, design maintenance is relatively simple. second, snowflake model In practice, with the addition and change of the fact table and

In the previous tutorial, we saw how to build cubes based on fact tables and dimension tables, and how to associate fact tables with dimension tables. This is the most common ing, that is, star schema. However, a dimension can be connected to a fact table based on more than one table by defining a well-defined path. This dimension is called Snowflake and uses

principles Building a large scale SaaS app Scaling an early stage startup Connected Star Podcast Architecture (original in Zhang Yi blog, but later article removed, it is a pity. This is reproduced) QQ game millions of people at the same time online server architecture implementation Research on construction Technology of large Web2.0 site On the distributed storage of Web site database Discussion on the structure of QQ Notes from Sca

I believe that friends who have used this attribute may be confused by this attribute. during use, it is often confusing to check and report errors. I think there is nothing wrong with this attribute, if you can write or set it again, but you cannot tell why. The official document on this attribute is not detailed. Online users also have different opinions on this attribute. A typical online discussion post is: what is the role of elementFormDefault = "qualified" in

recent projects are not in a hurry, decided to integrate some common, common content in a project framework, intended for the new project can be quickly set up, in fact, after several projects, there are always some duplication of the creation of work, you can use the content of this project directly to develop, using the MVC layered mode, This article will focus on the division of hierarchies and some of the third-party features that have been integrated; Of course, the source code for this pro

The following concepts are compiled after reading "no nonsense XML" and "XML manual version 4" in the Super Star PDG format 1. What is XML? Extensible markup language, that isScalability Markup Language. A tag is an information symbol that a computer can understand. Through this tag, a computer can process various types of information. Article . To define these tags, you can either select an international markup language, such as HTML, or use a mar