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Query Store for Solving Query Performance Regressions

Query Store for Solving Query Performance Regressions

Query performance is a very important area of SQL server. We always have badly performance queries around.

Query store is the newest tool for tracking and resolving performance problems in SQL server.

In this article, we are going to have a look at some practical uses of SQL server Query store.

What is Query Store?

The query store has been described by Microsoft as a ‘flight data recorder’ for SQL server queries. It tracks the queries run against the database, recording the details of the queries and their plans and their runtime characteristics. Query store is per database feature and runs automatically. Once turned on, nothing further needs to be done to get it to track data. It runs in the background collecting data and storing it for later analysis.

Query store is available in SQL Server 2016 and later, and Azure SQLDB v12 and later. It is available in all editions of SQL server, even in Express edition.

How is Query store different from other tracking options?

We have had query performance tracking for some time though in the form of dynamic management views. Mostly, sys.dm_exec_query_stats and sys.dm_exec_query_plan and tracing tools like SQL server profiler and extended events.

So, what makes Query Store different? Let me start answering that by describing a scenario that I encountered a couple of years ago.

A particular critical system was suddenly performing badly. It had been fine the previous week and there have been no extended events sessions or profiler traces running historically. The admin had restarted the server when the performance problem started, just to make sure it was not something related to a pending reboot.

As such, there was no historical performance data at all and solving the problem of what happened, why the query performance is different this week was extremely difficult.

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Improve SQL Server Performance with Compression

Improve SQL Server Performance with Compression

SQL Server data compression is now available in all editions of SQL Server, starting with 2016 SP1.

In this Article, you will not only know how data compression will save space, you’ll also find out how compression can sometimes improve performance as well.

Space Savings vs. Performance

When I first heard about compression back in 2008, my first thought is that it would have a big performance penalty. Compression would save disk space, but it would probably decrease performance as the data was compressed and decompressed. It turns out that compression can improve performance instead. Because compressed data fits in a smaller number of data pages, there are decreased I/O requirements. Since I/O is generally the bottleneck in SQL Server, this can improve performance. Compressed data also has a decreased memory requirement. When querying compressed data, a smaller number of pages will be copied to the buffer pool. The one area that is impacted is CPU. You do need to have some CPU headroom because compression will require some additional CPU resources.

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The good thing is that if the workload is reasonably tuned, many SQL Server instances have more CPU resources than they need. One note of caution here. Don’t look to compression as the solution to solving major performance issues. You need to look at physical resources, configuration, indexing, and query tuning. The point I’m trying to make is that decreased I/O and better memory utilization will benefit the workload in many cases.

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WordPress Annual Report to my SQL Server Community

I completed 4 Years as SQL Server blogger with my small Community SQL Server Consultation Community (http://mostafaelmasry.com)

I started it from 2012 and I will not stop sharing the information ad the new Technology in SQL Server

You can check the WordPress annual Report for the last 4 years from here

 

WordPress Annual Report to my SQL Server Community

 

 
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Posted by on January 1, 2016 in General topics

 

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