Live sexy chat srbija - Sql server updating data in a view
However, we can add a unique, clustered index to a view, creating an indexed view, and realize potential and sometimes significant performance benefits, especially when performing complex aggregations and other calculations.In short, if an indexed view can satisfy a query, then under certain circumstances, this can drastically reduce the amount of work that SQL Server needs to do to return the required data, and so improve query performance.
We’ll discuss these in more detail in the Listing 4 When we add a unique clustered index to a view, we ‘materialize’ it.
In other words, the ‘virtual table’ persists to disk, with its own page structure, and we can treat it just like a normal table.
Not only is this a good practice, it’s also a requirement when creating an indexed view (we’ll discuss further requirements as we progress).
Let’s assume that many applications need to run queries like this, joining the same tables, and referencing the same columns in various combinations.
For example, if one or more of the base tables is subject to frequent updates, then, depending on the aggregations we perform in the indexed view, it is possible that we will increase lock contention on the view’s index.
This article will start from the basics of creating indexed views, and the underlying requirements in order to do so, and then discuss their advantages and the situations in which they can offer a significant boost to query performance.
These examples assume you’re running SQL Server Enterprise Edition, which will automatically consider indexes on a view when creating a query execution plan, whereas SQL Server Standard Edition won’t; you’ll need to use the clause of any query you wish to use the view (more on this shortly).
When we re-run the query from Listing 3, we get the same result set, but the execution plan, shown in Figure 4, looks very different.
Views are a valuable tool for the SQL Server Developer, because they hide complexity and allow for a readable style of SQL expression.
They aren't there for reasons of performance, and so indexed views are designed to remedy this shortcoming.
Rather than several index scans with joins, the optimizer now determines that the optimal way to satisfy the query is to scan the clustered index of our view.Tags: Adult Dating, affair dating, sex dating