What is a materialized view and how does it differ from a view in SQL?

View is a named query and it doesn't store anything. When there is a query on view , underlying SQL statement gets executed and data is fetched from base table. Materialized view is also a named query. Unlike View, Materialized view stores data physically and get updated periodically. When there is a query on Materialized view, data is fetched from MV. Any changes happens to the underlying base table is reflected in View. Whereas in MV, data need to be refreshed manually or on a set schedule.

A view is a database object which is based on query which runs on one or more tables / views / functions. It does not hold any data but stored as a named query in the database and can be used to hide complex data extraction requirements to present data to users. Views could be used to provide read only access to data ensuring security.

A view in SQL is a virtual table based on the result of a `SELECT` query. It doesn't store data itself but provides a way to present data from one or more tables in a specific format. Example: CREATE VIEW EmployeeSummary AS SELECT e.EmployeeID, e.FirstName, e.LastName, d.DepartmentName FROM Employees e JOIN Departments d ON e.DepartmentID = d.DepartmentID; You can query the view like this: SELECT * FROM EmployeeSummary WHERE DepartmentName = 'Sales'; Views are useful for: - Simplifying complex queries - Providing an additional layer of security by restricting access to underlying tables - Presenting data in a format that's more relevant to specific users or applications

Difference between View and Materialized View View: *Virtual table *Defined by SQL query *Dynamically retrieves data *No data storage *Always reflects the current state of underlying tables *May introduce performance overhead for complex queries *Suitable for simplifying data access and enforcing security policies Materialized View: *Physical copy of query result *Stored in database *Requires storage space *May become stale over time *Can significantly improve query performance *Requires periodic refresh *Suitable for improving query performance and data caching

Difference between View and Materialized View View: *Virtual table *Defined by SQL query *Dynamically retrieves data *No data storage *Always reflects the current state of underlying tables *May introduce performance overhead for complex queries *Suitable for simplifying data access and enforcing security policies Materialized View: *Physical copy of query result *Stored in database *Requires storage space *May become stale over time *Can significantly improve query performance *Requires periodic refresh *Suitable for improving query performance and data caching

A materialized view is like a snapshot of the data taken at the time when this materialized view was last refreshed, whereas a normal view always fetches latest data.

On the other hand a Materialized view is a view that is stored as a result of a query, which is very similar to a table. This data is not dynamically queried each time and does require you to manually/automatically refresh the data.

The example here explains what the materialized view but not how/where to use it. In other words, doesn't explain correctly the purpose of a materialized view. Description: A materialized view acts as a data 'snapshot' of the underlying view/table, at a given time. It is therefore detached from the main view and does not update on its own. Usage/purpose: Useful for situations where the data needs to be cached. Basically, the query need not be executed every time, instead the materialized view can be used. In any situation where the query call to the actual table is expensive, the materialized view can be used to fetch data quickly. However, If the data is outdated the materialized view can be updated.

Materialized view is another type of view. This view is act like a physical table. That is why, we need to manually refresh it. With the CREATE MATELIZED VIEW statement one can create this view.

A materialized view is like a snapshot of a query's results. Unlike regular views that dynamically generate data when queried, a materialized view physically stores those results. It's like taking a picture of the data at a certain moment. This precomputed data can speed things up a lot, especially for complex or frequently used queries, as it's already there and doesn't need to be recalculated every time. But, remember, it needs a little maintenance to stay synced up with the actual data in the database.

There are a few key differences. The first one being how the data is stored. The normal view the result of the SELECT query is not stored where as the Materialized view is. Secondly, is the execution. Normal views are executed each time when the query is referenced where as the materialized view is not and requires a manual refresh. Thirdly, with regular views the data will always be up to date as the query is always refenced. On the other hand materialized views will have more stale data because the result is stored, hence the need for a refresh.

A view is a virtual table created from a query expression that displays data from one or more base tables, but it is not stored physically and is updated every time it is accessed. It doesn't require disk space and may have slower performance due to real-time data retrieval. In contrast, a materialized view is a physical copy of the data stored on disk, precomputed for faster access, and updated manually or via triggers. While materialized views provide quicker performance, they use memory and require maintenance to stay updated. Views offer real-time, up-to-date data, while materialized views are optimized for performance, particularly in data warehousing.

Views are used when data is to be accessed infrequently and the data in a table gets updated on a frequent basis. In contrast, Materialized Views are used when data is to be accessed frequently and data in table not get updated on frequent basis.

Views are the logical and virtual copy of a table that is based on a predefined query. A materialized view stores the results of a specific query in the database. A view always reflects the current data in the underlying tables. Unlike views, since materialized views stores data persistently which means they need to be refreshed periodically to reflect changes in the underlying data. Views are typically used for simplifying queries and enhancing security by controlling access to data. Materialized views on the other hand are especially beneficial in scenarios where there are large datasets or where the cost of computing the view in real-time is high.

There are some differences between the view and the materialized view. First of all, the view is a very lightweight rather than metalized view. Secondly, materialized views are dynamic and views are static. Another point is, that the materialized view needs a manual refresh but for view does not need any manual refresh. Last but not least, the view is more convenient for ad hoc queries but the materialized view is more efficient for permanent queries.

Materialized views act as precomputed tables, storing query results physically, notably boosting performance, especially for complex or frequently used queries. In contrast, regular views are saved queries generating virtual tables dynamically from underlying data upon access. The charm of materialized views lies in their performance enhancement. They save us from recalculating intricate joins or aggregations with every query. However, they require regular maintenance for synchronization with underlying tables. Regular views, though less performance-oriented, simplify tasks. They handle complex queries, abstract table structures, and offer a more user-friendly database interaction.

Both views can improve query performance. By using views or materialized views one can avoid complex queries for the same data every time. Sometimes it also depends on different kinds of factors such as size, complexity of the queries and so many.

In general, I've gone from this, using views moves the complexity of SQL queries at least partially from the application layer to the database and helps hide the underlying data model. Materialized views have some negative impact on INSERT, UPDATE, DELETE queries, but speed up SELECT queries.

Materialized views can save you time and money, as it can be costly to process queries each time you need to retrieve data. And the faster you get this data, the more efficient your data analysis will be. Creating a materialized view may take up more storage space, but it's much faster than creating a standard view. A materialized view responds faster in comparison to a view. This is because the materialized view is precomputed and therefore doesn't waste time resolving the query or joins in the query that create the materialized view.

Think of VIEWs as an extension of a query. For me, they are best utilized if you want to simplify your SELECT statements or you want to store SQL statements in your databases.

If the data changes frequently, materialized views show outdated data if not refreshed. So, this logic is not always right. "views should be used if you need real-time data, if your underlying data is small or changes infrequently" also not very correct.

To choose between views and materialized views it actually depends on the query and also on the requirements. Views should be used for a small data set in which the data set is not changed daily or some one needs an ad hoc report. On the other hand, materialized views should be used for large data set which is changing frequently or someone wants to create a permanent report for it.

Materialized views over Views if you are looking for performance but the data could be outdated, you need to think into consideration how is the refresh mechanism, it will depend of specific database engine. Another point is the Materialized View requires space, today space is a minor issue in Database engines, but still something to consider. Views require more time for the query engine because it fetch the data from the underlying tables every time it executes a query, but your data is up to date for the same reason.

Views and Materialized Views are quite different from each other. Views are used when data is to be accessed infrequently and the data in a table gets updated on a frequent basis. In contrast, Materialized Views are used when data is to be accessed frequently and data in table not get updated on frequent basis. Views are virtual only and run the query definition each time they are accessed. Also when you need performance on data that don't need to be up to date to the very second, materialized views are better, but your data will be older than in a standard view.

Choosing between views and materialized views depends on our priorities. Views offer real-time data by dynamically generating results from underlying tables, simplifying complex queries. In contrast, materialized views store precomputed results, significantly boosting query performance. However, they require periodic updates to stay synchronized. So, for immediate data access and simplified queries, views work well, while materialized views excel in speeding up queries at the cost of periodic maintenance.

personally, I'm not a big fan of either of these approaches. using the view does not gain anything in terms of performance, especially the materialized view where we cannot rely on the actuality of the data. in my opinion, good query optimization, indexes, temporary tables, table variables, these are mechanisms for quality development of sql queries. however, one good use of views is with tables that use logical deletion to simplify queries against those tables. Of course, I am speaking as sql server developer, I can't say much about oracle databases.

Views are very helpful for the environment with Data Mesh architecture, when you have a central data team that owns main datasets and a domain team wants to reuse a subset of main dataset in their domain, it’s simple to create a view with a needed data from main dataset, and if there are changes in main dataset, it will instantly be reflected in domain dataset without a need to backfill if it would be a downstream table with the source table from central data team.

Not to use materialised views instead go for stored procedure, advantage being the execution plan is cached and improved performance can be seen. Normal views are seen everywhere where we want to have control over what data is being shared to whom.