Snowflake Views | Types of views in Snowflake | Materialized Views | Secure Views

Summary

In this episode of the Snowflake learning series, we explore the different types of views in Snowflake, including non-materialized views, materialized views, and secure views. Views allow users to access query results as if they were tables, and are used for various purposes such as securing sensitive data, simplifying complex queries, and improving performance. While non-materialized views are the most common, materialized views offer faster performance at the cost of storage, and secure views ensure sensitive information remains protected. This video provides practical insights into how to choose the right type of view for different scenarios.

Takeaways

• 😀 Views in Snowflake are database objects that allow you to access the result of a SELECT query as if it were a table.
• 😀 You cannot perform DML operations directly on views, but changes in underlying tables are reflected in the views.
• 😀 Views can be used for security purposes, restricting access to specific columns or rows, such as hiding sensitive data like salaries.
• 😀 Views simplify complex queries for end users by hiding complex logic, making data analysis easier.
• 😀 Materialized views store pre-computed results to improve query performance by eliminating redundant processing.
• 😀 Non-materialized views are the most common type, executing the SELECT query every time without storing results, resulting in slower performance but no additional storage costs.
• 😀 Materialized views are ideal when base data changes infrequently and query performance is crucial, though they come with additional storage and compute costs.
• 😀 Materialized views can also be used to store data from external tables, improving performance when querying external data sources.
• 😀 Secure views offer extra security by preventing users from inferring underlying database structure and protecting sensitive data from unauthorized access.
• 😀 Secure views are generally slower than non-secure views but are recommended for scenarios where data protection is critical to prevent breaches.
• 😀 It is important to balance the use of materialized views, considering their cost versus the benefit of improved performance and query frequency.

Q & A

What are views in Snowflake and how do they function?

Views in Snowflake are database objects that allow the result of a SELECT query to be accessed as if it were a table. The SELECT query is defined in the CREATE VIEW DDL statement, and while you cannot perform DML operations (insert, update, delete) directly on views, any DML operations on the underlying tables are reflected in the views.

What are the primary use cases of views in Snowflake?

Views in Snowflake are used for a variety of purposes including enhancing security by restricting access to sensitive data, reducing complexity by simplifying complex queries, and improving performance through materialized views which store pre-processed query results for faster access.

How do views enhance security in Snowflake?

Views help enhance security by restricting access to specific rows or columns in the underlying tables. For example, if salary data is sensitive, a view can be created that only exposes non-sensitive columns, ensuring that unauthorized users cannot access confidential information.

What are non-materialized views and how do they work?

Non-materialized views in Snowflake are essentially just SELECT queries that are executed each time the view is queried. They don't store results for future use, meaning there are no additional storage costs, but they may have slower performance compared to materialized views because the query is executed each time.

How do materialized views differ from non-materialized views?

Materialized views store pre-computed results from a SELECT query and refresh automatically when the underlying data changes. This results in faster query performance since the data is already computed and stored, but it incurs additional storage and compute costs, unlike non-materialized views.

What conditions should be met to consider using materialized views in Snowflake?

Materialized views are recommended when the underlying base table doesn't change frequently, the results are used frequently, and the SELECT query is complex and resource-intensive. An example use case is a salary table where data updates infrequently but needs to be queried often.

Can materialized views be used with external tables in Snowflake?

Yes, materialized views can be created on top of external tables. This allows Snowflake to maintain a local copy of data that is stored outside of Snowflake's environment, improving query performance on external data.

What are secure views, and why are they important in Snowflake?

Secure views are a special type of view in Snowflake that provide additional security by preventing users from seeing the DDL of the view and reducing the risk of exposing underlying table structures. They also restrict certain query optimizations to prevent unauthorized data exposure, making them essential for protecting sensitive data.

How do secure views differ from non-secure views in Snowflake?

Secure views offer additional protections against unintended data exposure by limiting query optimizations that might reveal sensitive information. For example, when a secure view is defined, Snowflake ensures that query predicates in the view are applied first, preventing users from accessing unauthorized data even through complex queries.

When should you define a view as secure in Snowflake?

You should define a view as secure when dealing with sensitive data that you want to protect from unauthorized access. While secure views are generally slower than non-secure views due to limited optimization, they provide crucial security benefits by ensuring sensitive data is not exposed unintentionally.