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sys.query_store_query_variant (Transact-SQL)

Applies to: SQL Server 2022 (16.x) and later versions Azure SQL Database Azure SQL Managed Instance SQL database in Microsoft Fabric

Contains information about the parent-child relationships between the original parameterized queries (also known as parent queries), dispatcher plans, and their child query variants. This catalog view shows all query variants associated with a dispatcher and the original parameterized queries. Query variants share the same query_hash value as viewed from sys.query_store_query. When you join sys.query_store_query_variant with sys.query_store_query and sys.query_store_runtime_stats, you can obtain aggregate resource usage statistics for queries that differ only by their input values.

Column name Data type Description
query_variant_query_id bigint Primary key. ID of the parameterized sensitive query variant.
parent_query_id bigint ID of the original parameterized query.
dispatcher_plan_id bigint ID of the parameter sensitive plan optimization dispatcher plan.

Remarks

Because more than one query variant can associate with a single dispatcher plan, multiple plans belong to query variants and contribute to the overall resource usage statistics of the parent query. The dispatcher plan for query variants doesn't produce runtime statistics in the Query Store. As a result, existing Query Store queries aren't sufficient for gathering overall statistics unless you include an extra join to the sys.query_store_query_variant view.

Permissions

Requires the VIEW DATABASE STATE permission.

Permissions for SQL Server 2022 and later

Requires the VIEW DATABASE PERFORMANCE STATE permission on the database.

Examples

View Query Store variant information

SELECT 
    qspl.plan_type_desc AS query_plan_type, 
    qspl.plan_id as query_store_planid, 
    qspl.query_id as query_store_queryid, 
    qsqv.query_variant_query_id as query_store_variant_queryid,
    qsqv.parent_query_id as query_store_parent_queryid,
    qsqv.dispatcher_plan_id as query_store_dispatcher_planid,
    OBJECT_NAME(qsq.object_id) as module_name, 
    qsq.query_hash, 
    qsqtxt.query_sql_text,
    convert(xml,qspl.query_plan)as show_plan_xml,
    qsrs.last_execution_time as last_execution_time,
    qsrs.count_executions AS number_of_executions,
    qsq.count_compiles AS number_of_compiles 
FROM sys.query_store_runtime_stats AS qsrs
    JOIN sys.query_store_plan AS qspl 
        ON qsrs.plan_id = qspl.plan_id 
    JOIN sys.query_store_query_variant qsqv 
        ON qspl.query_id = qsqv.query_variant_query_id
    JOIN sys.query_store_query as qsq
        ON qsqv.parent_query_id = qsq.query_id
    JOIN sys.query_store_query_text AS qsqtxt  
        ON qsq.query_text_id = qsqtxt .query_text_id  
ORDER BY qspl.query_id, qsrs.last_execution_time;
GO

View Query Store dispatcher and variant information

SELECT
    qspl.plan_type_desc AS query_plan_type, 
    qspl.plan_id as query_store_planid, 
    qspl.query_id as query_store_queryid, 
    qsqv.query_variant_query_id as query_store_variant_queryid,
    qsqv.parent_query_id as query_store_parent_queryid, 
    qsqv.dispatcher_plan_id as query_store_dispatcher_planid,
    qsq.query_hash, 
    qsqtxt.query_sql_text, 
    CONVERT(xml,qspl.query_plan)as show_plan_xml,
    qsq.count_compiles AS number_of_compiles,
    qsrs.last_execution_time as last_execution_time,
    qsrs.count_executions AS number_of_executions
FROM sys.query_store_query qsq
    LEFT JOIN sys.query_store_query_text qsqtxt
        ON qsq.query_text_id = qsqtxt.query_text_id
    LEFT JOIN sys.query_store_plan qspl
        ON qsq.query_id = qspl.query_id
    LEFT JOIN sys.query_store_query_variant qsqv
        ON qsq.query_id = qsqv.query_variant_query_id
    LEFT JOIN sys.query_store_runtime_stats qsrs
        ON qspl.plan_id = qsrs.plan_id
    LEFT JOIN sys.query_store_runtime_stats_interval qsrsi
        ON qsrs.runtime_stats_interval_id = qsrsi.runtime_stats_interval_id
WHERE qspl.plan_type = 1 or qspl.plan_type = 2
ORDER BY qspl.query_id, qsrs.last_execution_time;
GO

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