Metadata in data warehouse is a kind of data that provides information about other data. The information that metadata provides helps us in understanding the structure, context, and nature of the data that it points to. Thus, it also helps in the easy search and retrieval of data.
In short, metadata is a short explanation or a summary of what the data is. The more humans are creating and interact with the data, they are creating more information about the data. In this particular content, we will discuss more metadata. How it is important in the data warehouse? What are the different kinds of data types?
Metadata in Data Warehouse
- What is Metadata in Data Warehouse?
- How Does Metadata Works?
- Why Metadata is Important?
- Types of Metadata
What is Metadata in Data Warehouse?
Metadata in the data warehouse is used to identify the objects of the warehouse. It is similar to the data dictionary of a database. Just like a data dictionary has information about the database such as logical structures, files, addresses, indexes, etc.
Let’s try to understand the concept of metadata with the help of an example. You might have heard about the yellow pages (a telephone directory that has advertisements and phone numbers of the businesses and organizations of your town). The yellow pages provide you with information about the stores in your town, their location, names, and about their products.
In the same way, the metadata serves as a directory of the data present in the data warehouse.
How Does Metadata Works?
Now how metadata work totally depends on the kind of information it is defining. Let us understand the working of metadata with the help of some scenarios.
Metadata of websites
While preparing content for a website we also add a meta description for each piece of content. The search engine reads this meta description and identifies the keywords from it. These keywords help the search engine in categorizing the website.
Now whenever the user will search for a particular keyword in the search engine, it will display the websites with the matching keywords. So, this meta description helps the website to appear in the search result.
The other data of the websites that act as metadata are the title of the contents, tags, headings, etc.
Whenever a user visits any website, the website collects some of the user’s information that helps the concerned companies in tracking their consumers.
For suppose you visit an online shopping website. Now, this website will track information such as where did you click on the website, what did you purchase, what you surf, what’s the location of your device, what kind of device you used to surf the website, etc.
All this information act as metadata for the companies that define your behavior to them and help them in marketing their product in a better way to maximize their profit.
Maintaining Files and Folders
While using a computer you create many files and folders. With each file and folder, there is information attached such as:
- Date of creation
- Date modified
- Last seen
- Size of file
- Who is the creator
- What kind of file it is, and many more.
All this information act as metadata for the file. It helps the operating system in identifying which program it must use to open a particular file. Thus, the metadata attached to computer files and folders helps in executing and maintaining them.
We all know that database is a collection of data (records) in the form of tables. These tables have column names, and row names which act as metadata. This metadata helps the user to store, organize and retrieve data. The metadata here also helps the user to identify relationships between several records in the database.
Why Metadata is Important?
Metadata provides the information that connects all the parts of the data warehouse.
Metadata provides the information that helps developers to understand the context and structure of the data in the data warehouse.
It enables the end-user to extract useful information for benefit of their business.
Thus, the metadata helps the user to answer the question about the data in the data warehouse.
Types of Metadata
We know that metadata is the data that describes other data. So, if we categorize metadata on the basis of the type of data it describes it can be of three types:
- Operational Metadata
- Extraction and Transformation Metadata
- End-User Metadata
Operational metadata defines the data that operational systems of several enterprises/organizations/companies produce. Every operational system produces data with different data structures. You must be thinking about how the operational metadata works. Well while selecting data from this operating system we have to split the record, combine the parts of records from different source files, and provide the information to the end users. Operational metadata allow us to do so. Even after delivering information to the end user, the system must be able to tie back the information to its original source. Operational metadata contains the data that has information to reverse back to the original data sets.
Extraction and Transformation Metadata
Extraction and transformation metadata is data that defines the extraction frequencies, extraction methods, and business rules that are essential for extracting data from the source system. This kind of metadata contains information about the transformation of data that takes place in the data staging area.
The end-user metadata contains the information that enables the end-user to extract information from the data warehouse. They can use the extracted information to enhance their business.
Thus, we can conclude that metadata is very important for extracting useful information from data warehouses.