Here are some answers to questions from PASS Performance Marathon presentation on Query Store: An Introduction

1. To turn on/off Query Store, will it impact DB availability? (meaning DB does not need to be offline)

No, turning off query store does not affect the availability of the database.

2. What was the name of the blog contact for query store again please

Erin Stellato of SQLSkills.com has lots of information about Query Store

3. What happen if a forced plan becomes invalid?
SQL Server will select a new/different plan. I demonstrated this in the session by deleting the column store index which was part of the forced plan and it used a different one.

4.

Why does even the SQL plan change right in the middle of the day?
It Depends. Many scenarios exist for plan changes – statistics out of date, new indexes available, thresholds for number of rows estimated to be return, etc.

5. Are there any performance issues with query store?
There have not been many reports of query store affecting performance, but it does happen. Either collection period and summarization is to low or a very, very busy system with lots of adhoc queries for transactions and reporting.

6. Say we wanted to let it run more often for general performance needs?

Yes you can, but watch the amount of data being collected with the properties of the database or DMVs.

7.

Can we manage Query Store information (such as retrieval) via t-sql or PowerShell?
Yes, Microsoft provides a GUI as well as T-SQL to accomplish almost anything in SQL Server plus PowerShell.