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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 offers the ability to view all query variants associated with a dispatcher as well as the original parameterized queries. Query variants will have the same query_hash value as viewed from within the sys.query_store_query catalog view, which when joined with the sys.query_store_query_variant and sys.query_store_runtime_stats catalog views, aggregate resource usage statistics can be obtained 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

Since more than one query variant can be associated with one dispatcher plan, there will be multiple plans that belong to query variants which will eventually add to the overall resource usage statistics of the parent query. The dispatcher plan for query variants does not produce any runtime statistics in the Query Store, which will cause existing Query Store queries to no longer be sufficient when gathering overall statistics unless an additional join to the query_store_query_variant view is included.

Permissions

Requires the VIEW DATABASE STATE permission.

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

See Also

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