Press "Enter" to skip to content

Category: Query Store

QDS Cache Cleanup in QDS Toolbox

Jared Poche continues a series on the QDS Toolbox:

When configuring Query Store, we have a few options for deciding how it retains data but little control over how it cleans up that data. We can set the max size of our query store, the max number of plans to keep per query, and how long to keep query statistics.

The QDS Cache Cleanup component of the QDS Toolbox gives us a number of other options for what data to remove:

Read on for that list and a good example of where it was useful.

Comments closed

Query Waits in the QDS Toolbox

Jared Poche continues a series on QDS Toolbox:

Carrying on from my previous post on the QDS Toolbox, let’s review the Query Waits component.

This component provides details about the wait types associated with a given object, query, or plan. This doesn’t pull data from the reports generated by the Server Top Queries component; this gets the data directly from the Query Store in the database you specify. So you can use this to review the waits on a given procedure, even if you haven’t generated any reports with Server Top Queries .

That being said, reports from Server Top Queries could identify problem queries and give you the PlanID, QueryID, or ObjectName you need to run the procedure. A query that spends a lot of time waiting would tend to have a higher duration and lower active metrics like CPU usage or logical reads. So those are the queries I would want to run the Query Waits report against.

Read on to see how to call this procedure and what you might expect.

Comments closed

Removing Data from Query Store

Erin Stellato shows us how to do some spring cleaning:

Automatic removal of data from Query Store is based on configuration, notably the MAX_STORAGE_SIZE_MBCLEANUP_POLICY (STALE_QUERY_THRESHOLD_DAYS), and SIZE_BASED_CLEANUP_MODE settings.  While these are detailed in another post, it’s worth reiterating that ideally, size-based cleanup never kicks in.  A database’s Query Store should be sized to accommodate N days’ worth of data, where N is set by CLEANUP_POLICY (STALE_QUERY_THRESHOLD_DAYS).  When the size of the Query Store exceeds 90% of MAX_STORAGE_SIZE_MB, and if SIZE_BASED_CLEANUP_MODE is set to AUTO, then clean up will kick in.  This algorithm is not efficient, and it runs single-threaded.  It looks for queries that are infrequently executed/less important and deletes those, one by one, until the size is less than 80% of MAX_STORAGE_SIZE_MB.  Avoid this type of cleanup if at all possible.

There is a better way. And an even better way thanks to some of my colleagues.

Comments closed

Having Fun with the QDS Toolbox

Jared Poche shares a few queries with us:

The QDS Toolbox is set of tools that can help you review and store the performance related data in Query Store. This was released by ChannelAdvisor last September thanks to the hard work of a number of my coworkers.

If you aren’t experienced with Query Store, this can provide a good starting point for getting familiar with data that is available and what you can do with it. If you are experienced with Query Store, this may give you an easy way to set up customizable reports that help you find issues and see trends.

The QDS Toolbox has several components, and I intend to post about each in turn. Two new components were added to this recently by @sqlozano (, bringing the current total to eight.

Click through for a deeper dive into the Server Top Queries report.

Comments closed

Required Permissions for Forcing Query Store Plans

Grant Fritchey reviews minimum requirements:

I was recently asked what permissions were needed to force plans in query store. I’m sure I knew at one point, but at the moment I was asked, I couldn’t remember to save my life. So, I went and looked it up. In the interest of sharing, especially for the poor person who I left hanging, here’s what I found.

Click through for the disappointing answer.

Comments closed

Query Store Hints

Erin Stellato takes a look at a new Microsoft announcement:

Query hints can be really helpful in some scenarios, but if you do not have direct access to the code (hello third party applications), then you cannot add a query hint to the statement.  Historically, you’ve been able to use a plan guide to apply a hint, and that doesn’t require direct code access, but plan guides are not always intuitive and I find that most people are not familiar with how to use them.

Enter Query Store Hints.  With this feature, you can now add a hint to a specific statement, even if you don’t have access to the code base.  

Read on to see what it does and how you can use it.

Comments closed

Wait Stats Not in Query Store

Erik Darling says wait, wait, don’t tell me:

There are some oddities in the documentation for query store wait stats.

One is that RESOURCE_SEMAPHORE_QUERY_COMPILE is listed as a collected wait, but with an asterisk that says it’s not actually collected. I’ve tested workloads that generate lots of that wait, and just like the docs say, it doesn’t end up there.

Of course, since I added wait stats recently to sp_QuickieStore, I wanted to make sure other waits that I care about actually show up in there.

Read on to see which wait stats you can find in Query Store and which you’ll have to get from someplace else.

Comments closed