We store the data in the form of tables, but to make the accessibility of the table custom, there comes a concept of views.
The table is stored in the physical memory of the database, while the Views are the concept of a virtual table that helps to access the data of the actual table in the custom form. These are the most important concept of the database management system.
In this article, we will see the difference between the view and materialized view to understand more about the database management system.
Views are virtual tables created with the select query's help. Views are not stored in the physical memory. These are created whenever a query is accessed, and we get an updated list in a view when the query is fired. We can create a virtual table by taking any data from the actual table, and even we can take the data from many tables, which means we can create a view with some entities of one table and some from another table.
If we update any data in the table, it will be seen in the view and vice-versa.
Syntax in View
Let, we have to create a view as basicDetails with two columns of Roll no and Name of Class 7 from the table Students with five columns.
CREATE VIEW basicDetails AS
SELECT Rollno, Name
FROM Students
WHERE Class = “7”;
After running the above query, the required view will be created.
Properties of Views
Views are an essential database concept, and some of the properties of views are as follows.
Views are virtual tables containing data per the user's requirement.
Views can easily be created by joining many tables, which means we can create a view from multiple tables according to our requirements.
Views do not cost any extra storage associated with them.
The complexity of data can be hidden by views, making it easy to manage the data in the database.
What do you mean by Materialized View?
The materialized view is also known as virtual tables, but the difference between the view and the materialized view is that materialized views are stored in physical memory. The definition of the query is also stored in the database. Materialized views are the physical copy of the original table. It also contains the only required data, which are not updated automatically after being updated in the actual table. Still, the user has to change the data manually in this view.
This process of updating the data manually in a materialized view is known as Materialized View Maintenance.
Syntax in Materialized View
Let, we have to create a materialized view as basicDetails with two columns of Roll no and Name of Class 7 from the table Students with five columns.
CREATE (Or REPLACE) MATERIALIZED VIEW basicDetails
AS
SELECT Rollno, Name
FROM Students
WHERE Class = “7”;
After running the above query, the required view will be created.
Properties of Materialized View
Unlike standard views, materialized views are also important, and their properties are as follows.
As the same subquery results in the materialized view so the performance of the query is optimized.
Materialized views do not update the data in the view automatically, so users have to update it manually. This will decrease the chance of any error during the updation of any error.
The table created by the materialized view is indexed in the database to be accessed more quickly and efficiently. So it is also known as ‘indexed views”.
Snowflake is a background service that helps materialized views to be maintained automatically.
To understand these views, you need to understand the difference between view and materialized view.
So, let's discuss the difference between the view and materialized view with the help of the below table.
View
Materialised View
This view of the table is a virtual table created with the help of “select query.” To get the view, we have to fire the same query again, as this view does not get stored in the physical memory.
This view is also a virtual table, and it is also created with the help of “select query,” but these views are stored in physical memory, so we don’t have to run the query again and again.
When the data is updated in the actual table, it is automatically updated in the view.
In materialized view, the user must manually update the data after updating it in the actual table.
This view does not cost extra memory as the table is not stored in the database.
The materialized view is stored in the physical memory, costing some memory in the database.
When the particular data is used infrequently, we must use this view.
When we have to use data frequently, we should use the Materialized view.
This view responds very slowly, which deceives the performance of the query.
This view is faster as compared to the normal view.
Which view must be used if the data is required infrequently?
We should use the normal view instead of materialized view because it does not store the data in memory, so we can fire the query repeatedly as we require the data infrequently and save space in the memory.
What are virtual tables in the views?
Virtual tables are made with the help of an actual table at the time of the requirement of the particular set of data that we have to use in the code, and it helps in the database management system.
Which view is known as an “indexed table” and why?
The materialized view is known as the indexed table, as the table which is created by this view is indexed in the database to access that data more quickly and efficiently.
What is the main difference between the view and materialized view?
The main difference between the view and the materialized view is memory storage, meaning that the view is not stored physically in the memory. In contrast, the materialized view is stored in the memory physically.
Conclusion
In this article, we learned about the important concept of the database management system, that is views. We also saw the definition, uses, and properties of views and also saw the difference between view and materialized view, in which we learned that the normal view does not cost any memory as it is not stored anywhere, while materialized views are stored in the memory physically. Hence, it takes up some space in the system.
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