Query Store – Quick Tour

The query store, Borko Novakovic Senior Program Manager from Microsoft calls this feature “Similar to an airplane’s flight data recorder”.

To get this setup there are some pre-Reqs needed. First you need the latest version of SSMS https://msdn.microsoft.com/library/mt238290.aspx – download it and install it.  This blog post is just a whirl wind / high level post on query store, you could write a book on it.

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Anyways, next comes the fun part – enabling it.

ALTER DATABASE [OURDB] SET QUERY_STORE = ON;

Why I said you need the latest version of SSMS is because it exposes the functionality via the GUI. You will see the query store node.

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Once enabled you have a plethora of information at your finger tips – and I am really impressed with it. Now there is no real need to dig into the plan cache to get the information, or a need to run XML to parse data. It’s all here ready for use.

Beware of some default configuration options:

  • The number of days to retain data in the query store. The default value is 30.
  • The default value is 900 seconds (that is when data written to the query store is persisted to disk).
  • MAX_STORAGE_SIZE_MB limit is 100MB
  • Time interval at which runtime execution statistics data is aggregated into the query store. The default value is 60.
  • SIZE_BASED_CLEANUP_MODE – this is whether or not the cleanup process will be automatically activated, auto is the default option.
  • QUERY_CAPTURE_MODE for Azure the default is AUTO meaning ignore infrequent and queries with insignificant compile and execution duration
  • MAX_PLANS_PER_QUERY = 200.

You can change these settings via SSMS under database properties.

Please Note: Query store data is stored within the host database.

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Let’s have a look at “Top Resource consuming queries” option. This is just 1 area of analysis, as mentioned before there is alot of information within query store that you could analyse.

You have the ability to analyse the following metrics:

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For this example I was looking at CPU (AVG).

You have 3 windows presented (for this example)

  1. This is a bar chart showing you query id’s – usually you select one of interest
  2. Shows you the plan summary for that specfic query
  3. Will give you the execution plan for the above plan id.

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It’s so powerful you even have the option to FORCE a plan, something that you may want to consider before actually pressing that button.  Saying that, I have the below situation – you know what I am going to do right?

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