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In the world of database management, it is essential to understand the performance characteristics of different query constructs. Today, we'll be exploring a comparison between views and inline table-valued functions (TVFs) across various database technologies, including SQL Server 2012, SQL Server 2014, MySQL 5.6, DB2 10.5, and Azure SQL Database.

Views and inline TVFs are two powerful tools for encapsulating database logic. A view is essentially a stored query that you can treat like a table, while an inline table-valued function is a function that returns a table. But which one offers better performance? The answer is not straightforward, as it depends on various factors, including the database technology being used, the complexity of the underlying query, and the specific use case.

Let's start with SQL Server 2012 and 2014. In general, both views and inline TVFs have similar performance characteristics in SQL Server, as both are expanded into the calling query and optimized together with it. However, there can be differences under specific circumstances. For example, consider the following T-SQL code:

CREATE VIEW vw_example AS 
SELECT ... -- complex query
GO
SELECT * FROM vw_example WHERE ... -- filter

In this case, SQL Server will optimize the entire query in the view, including the parts that might be unnecessary given the filter in the calling query. An inline TVF, on the other hand, would allow the optimizer to push the filter down into the function, potentially leading to a more efficient execution plan.

MySQL 5.6, on the other hand, does not support inline TVFs but does support views. However, the optimization of views in MySQL is somewhat limited, and under certain circumstances, a view might lead to a less efficient execution plan than the equivalent query written directly against the base tables.

DB2 10.5 also supports both views and inline TVFs, and like SQL Server, it optimizes them together with the calling query. However, DB2 has a feature known as "predicate pushdown," which can often result in more efficient execution plans for inline TVFs compared to equivalent views, especially for complex queries with multiple filters and joins.

Finally, let's consider Azure SQL Database, Microsoft's cloud-based database service. Given its similarities to SQL Server, it's not surprising that it also supports both views and inline TVFs, and that it optimizes them in the same way. However, due to the nature of cloud-based database services, there might be other factors influencing the performance of views and inline TVFs in Azure SQL Database, such as network latency and the performance tier of the database.

In conclusion, while views and inline table-valued functions are similar in many ways, there can be significant differences in their performance characteristics, depending on the specific database technology and the details of the query. Therefore, it's important to understand these differences and to test the performance of your queries in your specific environment.