Quickly understand the concept of multidimensional databases

A multidimensional database (Multi dimesional DATABASE,MDD) can be simply understood as storing data in an n-dimensional array, rather than storing it as a record as a relational database. So it has a lot of sparse matrices, and people can look at the data through multidimensional views. Multidimensional database adds a time dimension, compared with relational database, its advantage is that it can improve data processing speed, speed up reaction time and improve query efficiency.

There are currently two types of OLAP products for MDD: MOLAP based on multidimensional databases and ROLAP based on relational databases. ROLAP has established a new system, the star structure.

MDD does not have a recognized multidimensional model, nor does it have a standard way to get data, such as SQL, APIs, and so on, as in relational models. Based on MDD, OLAP products vary greatly depending on the content used for decision support.

At the low end, users use a single user or small LAN tool to observe multidimensional data. The functionality and practicality of these tools can be quite good, but they do not have all the features of OLAP due to size constraints. These tools use a hyper-cubic structure that restricts the model to n-dimensional morphology. This model will be vulnerable when the model is large enough and the sparse data is not well controlled. These tools use the size of the database to be measured in megabytes, rather than GB, so that only read-only operations and limited complex computations are available.

At the high-end, OLAP tools provide a perfect development environment, statistical analysis, time series analysis, financial reporting, user interface, multi-tier architecture, graphs and many other functions in 4GL. Although different OLAP tools use their own multidimensional databases, they also use relational databases as storage media to varying degrees. Because relational databases and OLAP tools are processed simultaneously on high-end servers, speed and efficiency are still fast.

The pure multidimensional database engine was also developed. Although these tools lack a 4GL and full development environment, they have a more complex database than the databases used by high-end MDD tools. These tools also feature statistical analysis, financial analysis, and time series analysis, and have their own APIs that allow them to be open to the front-end development environment.

MDD provides excellent query performance. The information stored in MDD has a more detailed index than the information in the relational database, and can often be ぴ flattery 诖 Little dd information is stored as an array, so it can update the data without affecting the index. So MDD is ideal for read and write applications.