Query Store Isn’t A Forensics Engine

Grant Fritchey shows that Query Store has a limited capability of finding “ill-behaving” queries at a point in time:

Here’s a great question I received: We had a problem at 9:02 AM this morning, but we’re not sure what happened. Can Query Store tell us?

My first blush response is, no. Not really. Query Store keeps aggregate performance metrics about the queries on the database where Query Store is enabled. Aggregation means that we can’t tell you what happened with an individual call at 9:02 AM…

Well, not entirely true.

Query Store isn’t a total solution for “Why was the system slow at XX:XX?” types of questions.  This does not diminish its value as long as you do not try to treat it as your only monitoring solution.

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When A Database In An AG Has Different Query Store Settings

Erin Stellato explains how we can have a discrepancy in Query Store settings between the primary and a secondary in an Availability Group: Last week there was a question on #sqlhelp on Twitter about the status of Query Store for a database in an Availability Group. I’ve written about Query Store and Availability Groups before so if […]

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How Query Store Stores Date Data

Erin Stellato shows us a few nuances to the way that Query Store handles dates internally: Query Store retains query performance data at the plan level.  This data is then broken out into intervals of time, determined by the INTERVAL_LENGTH_MINUTES setting.  The time intervals are found in the sys.query_store_runtime_stats_interval system view, and the start_time and end_time […]

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