Why are partitioned views useful

I had never really looked seriously at this feature since I thought it was mostly a convenience. The idea behind partitioned views is that you will have two or more tables with identical schemas, and you will use UNION ALL to combine the tables in a view. Now you can use the view to select the data instead of specifying the actual tables. When creating a partitioned view, you could place a table containing older data on slower, less expensive storage.

You could place the most active data in a table living on faster storage, such as on solid state disks. Adding new data to the partitioned view could be pretty quick as well. It may mean just modifying the view definition to include a new table.

What I had not realized, however, is that, if you design the tables correctly, you can also see a performance advantage. To demonstrate, run the following script to create and populate two tables. This example is simple, but we could place each table into a different file group and even a different storage tier. The next step is to create the partitioned view. DataActive ; GO.

It will show exactly which tables are being accessed. Run this query and check the Messages tab. To fix this issue, you must add check constraints to the tables which will allow SQL Server to ignore tables that are not needed in a particular query. You should also refresh the view definition. Make the changes and run the query again. DataActive ;. What about data modifications? It seems like you would have to make those directly to the underlying tables, but that is not the case.

As long as you filter on the column that divides the data, you can also make updates. I did see that it might be better to make the changes directly to the tables to get the best performance. You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. This site uses Akismet to reduce spam. Learn how your comment data is processed. Menu Skip to content sqlsunday. Search for:. Partitioned views Luckily, you can create your own partitioning.

Rate this:. Like this: Like Loading Let me hear your thoughts! Cancel reply Enter your comment here Fill in your details below or click an icon to log in:. Email required Address never made public. Name required. Follow Following. I totally voted for your Connect item. This is purely due to optimizer limitations since the optimizer could break up a partitioned table access into branches, of course.

That gets a merge concat with N-1 merges for partitioned views. A partitioned table cannot produce a sorted stream of rows directly because the stream will be sorted by PartitionKey, ClusteringKey. But from Exchange, in the HTML email, with the obsfucated Mailchimp or whoever links, I get really weird inconsistent, depending on what link I clicked previously in the article results. For debugging purposes, this is an email opened in Outlook , with Edge set as the go-to Browser.

Hi, I have a problem with partitioned view. The answer in this case is that table elimination within a partitioned view generally requires you to have a predicate that guarantees that the table can be eliminated from the plan at compile time.

This is not the case for your join, in which SQL Server cannot prove that tables are able to be eliminated until run-time. In most cases a potential exception being a loop join with a startup filter, for example , this means you will not get table elimination and you may suffer a significant performance degradation.

This will allow table elimination, sometimes vastly improving performance. This is an imperfect solution in several ways, however: It might require application code changes, and it might also impact cardinality estimates. So, how would you add an Index to a View that pulls from a Partitioned table? I have a table script to create a table — showing just the first and last lines.

As you can see, the last part of the script specifies the Partition Scheme and partitioning field. DrugPrice GO. But we have another View with this to create an Index, and it specifies the [Primary] filegroup.

If adding an Index to this new View of an Partitioned table, do I need to refer to the Partition Scheme, or just the [Primary] filegroup? We are looking at a partitioned view as a replacement for a very large table, following your example of annualized tables. Our reason is to improve the index maintenance cycle. To your knowledge is their any practical limit to how many tables are in a partitioned view? For example, if monthly tables were used over a 30 year period ie tables , would the partitioned view work as well?

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