How do views compare to tables when it comes to database optimization?

In my experience as a DBA, views and tables are used in different ways in SQL. Basically, tables are physical storage structures where data is physically stored on disk, while views are representations of data sets derived from tables, thus being logical storage. Views can simplify complex queries, and knowing how to use them can generate better performance in query executions, as long as they are maintained regularly, because updates and recalculations of views can affect performance. Another benefit is related to security, as it gives us access to data without the risk of altering or deleting the physical data stored.

As an Oracle DBA expert, views offer optimization benefits compared to tables in certain scenarios. Views act as virtual tables, representing data from one or more real tables. They simplify complex joins, abstract data, and restrict access, enhancing query performance and security. By presenting tailored data to users, views reduce unnecessary data processing, improving performance. Moreover, views can enforce data access restrictions, enhancing security by exposing only relevant data to specific users. However, views might introduce overhead due to query execution, so careful consideration is necessary for optimal performance.

Views: Provide abstraction and security by simplifying complex queries and controlling access to data. Can improve efficiency and performance by predefining joins and aggregations, and caching query results (materialized views). Tables: Offer flexibility and persistence in storing and managing data. Provide functionality and control through constraints, indexes, triggers, and foreign keys to maintain data quality and relationships.

Views act as a sort of window into data, offering a convenient way to manipulate and present information stored in underlying tables. Their utility lies in their ability to simplify complex operations, provide a level of abstraction, and control access to sensitive data. For instance, they enable displaying to a user only the information relevant to them, thus enhancing both efficiency and security by reducing unnecessary data processing and restricting exposure to confidential data. In summary, views are a powerful tool for optimizing queries and bolstering data security.

Tables are the primary storage mechanism for raw data in a database, optimized for efficient data storage, retrieval, and manipulation. They enforce data integrity constraints and support indexing for improved query performance. On the other hand, views are virtual tables generated dynamically based on predefined SQL queries. They offer data abstraction, query optimization, and security benefits by presenting a simplified or transformed view of the underlying data. Both tables and views play important roles in database optimization, and their usage should be tailored to the specific requirements and goals of the application

As an Oracle DBA expert, tables serve as the foundation of relational databases, storing data physically in rows and columns. Optimization strategies like indexing, partitioning, and normalization are crucial for enhancing query performance by minimizing I/O operations and ensuring efficient data retrieval. Unlike views, tables directly handle insert, update, and delete operations, which can lead to fragmentation over time. Regular maintenance, including defragmentation and statistics updates, is necessary to maintain optimal performance for table-based queries.

In Oracle, we can use Materialized View (MV) to speed up query. Queries to databases often involve joins between tables or aggregations such as SUM, or both. These operations are very expensive in terms of time and resource consumption. The type of MV that is created determines how the MV can be refreshed. MV improve query performance by precalculating expensive join and aggregation operations on the database prior to execution time and storing the results in the database. Queries are directed to the MV and not to the underlying detail tables, thus reducing repetitive IO to table. In general, rewriting queries to use MV rather than detail tables results in a significant performance gain

Views sit on top of table(s), so their performance will depend upon how well the table(s) are defined. The most obvious item is the indexing - are the indexes well defined for the most likely querying purposes? A view may sit on top of only one table, but more likely it's the result of joins to several tables. Are those joins correctly defined and on indexed fields? Other 'performance' factors, in my opinion, include 'ease of use' and 'usefulness'. A view that takes a few extra moments to render - but returns a treasure-trove of useful info faster than querying the underlying tables individually - may be worth the wait. The long and short is that a view is a query -- so you can tune the view by tuning the query that defines it.

As an Oracle DBA expert, views provide performance advantages by simplifying complex queries and offering a streamlined interface for data retrieval. However, their performance is closely linked to the optimization of underlying tables. Well-indexed and structured tables can enhance view performance, but poorly optimized base tables may negate any benefits. Views can introduce overhead if overly complex or dealing with substantial data. Thus, while views can optimize performance, they rely heavily on the efficiency of underlying table structures for optimal results.

Well constructed "Views" simplify access to data and produce faster responses, than directly querying the Tables. However, proper management of Tables indexing is necessary. Improper build of "Views" or that query very large size of data may result in less performance than querying the table directly.

As an Oracle DBA expert, maintenance is a crucial factor in database optimization. Views generally require less maintenance as they don't store data themselves. However, it's essential to ensure the underlying tables are well-maintained. For views, keep SQL code optimized and aligned with schema changes. Tables demand regular upkeep like index rebuilding, statistics updates, and fragmentation monitoring. Consistent maintenance is key to ensuring efficient and fast queries against tables.

Views allow you to expose only the necessary columns and rows to users, hiding sensitive data from unauthorized access. By granting users access to views instead of base tables, you can control precisely what data they can see. Views enable fine-grained access control by allowing you to apply permissions at the view level. You can grant SELECT, INSERT, UPDATE, or DELETE permissions on views to specific users or roles, restricting their actions to the data presented by the view. Views can be used in conjunction with column-level security features such as dynamic data masking or encryption to mask sensitive data before presenting it to users.

As a oracle n mysql dba, I feel data security is definely a benefit. Access to data can b controlled based on roles n responsibilities

Views shine in the area of security. The underlying table(s) may have PII fields (such as social security number) that are used to join the various underlying tables together, but the PII fields are either not displayed or the values are masked in the final result. The view shows only the fields defined by the query - not all the fields on the source tables - thus leaving PII protected. Less fields coming back also makes the view both more useful and easier to use - the audience sees only what they need to see for the purpose at hand.

As an Oracle DBA expert, views offer significant advantages in database optimization, particularly regarding security. They provide a layer of abstraction, allowing for fine-grained access control to specific data sets without exposing entire tables. This enhances security by safeguarding sensitive data while enabling necessary operations through the view. Moreover, restricting the scope of data accessible via views can enhance performance by reducing the workload on the database, resulting in faster query execution. Overall, views contribute to both security and performance optimization in database management.

Once upon a time I got a task about to add a change to reports. And, under the hood these reports used a different queries in it but one part was the same. A values calculation formula. The worst of this - you need to change each report every time when it is necessary to change calculation. It is not difficult but it is boring routine. So, I did a view instead of table and encapsulate a calculation formula into that view. With this approach I can simplify query and if I need to change calculation I can do this in one place. It looks obviously, but for some reason people don't use it sometimes.

In my opinion it's a value-add to be able to turn a business request for data around quickly and views are a tool that lend themselves to that ability. Dashboards come and go daily - the views that power them can do the same. A well-defined view that has a specific purpose can pull (and aggregate) far fewer fields for final display than exist on the underlying tables -- thus making them perfect for 'turn on a dime' needs from the various business teams. Various views can be created quickly off of the same set of underlying tables, based on the spec-du-jour, all while protecting PII - and they can be dropped just as quickly once the need has passed, again without having to touch the underlying tables.