Forcing Query Store Plans

Grant Fritchey wonders, if you force a plan using Query Store but the plan ages out of cache, do you still use the forced plan?

To start with, a small stored procedure that I use all the time for bad parameter sniffing demos that reliably gets different plans with different values due to statistics skew:

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CREATE PROC dbo.spAddressByCity @City NVARCHAR(30)
AS
SELECT  a.AddressID,
        a.AddressLine1,
        a.AddressLine2,
        a.City,
        sp.Name AS StateProvinceName,
        a.PostalCode
FROM    Person.Address AS a
JOIN    Person.StateProvince AS sp
        ON a.StateProvinceID = sp.StateProvinceID
WHERE   a.City = @City;

If this procedure is called for a value of ‘London’ it gets a plan with a Merge Join. For most other value it gets a plan with a Loops Join. Here’s an example of the ‘London’ plan:

It’s a good question with a good answer.

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Recompile Hints and Query Store

Erin Stellato answers two questions relating to recompile hints and whether those queries show up in Query Store: Last week in our IEPTO2 class I was asked about queries with OPTION (RECOMPILE) and Query Store. Specifically: Do queries that have the OPTION (RECOMPILE) hint go into Query Store, AND do queries in a stored procedure created with the RECOMPILE […]

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Forcing Plans with Table Variables

Grant Fritchey takes us through an interesting scenario around Query Store: This weekend I was in Stockholm in Sweden, talking Query Store and plan forcing with Steinar Anderson, when he mentioned the problems he had while forcing plans that had table variables in them. Don’t panic. Of course you can force a plan with a table […]

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