Find Parameter Sniffing Candidates with Query Store

SELECT TOP 20 q.query_id,
       COUNT(DISTINCT p.plan_id) AS plan_count,
       MIN(rs.avg_duration) / 1000 AS min_avg_ms,
       MAX(rs.avg_duration) / 1000 AS max_avg_ms,
       MAX(rs.avg_duration) / NULLIF(MIN(rs.avg_duration), 0) AS ratio,
       LEFT(qt.query_sql_text, 150) AS query_text
FROM sys.query_store_query q
JOIN sys.query_store_query_text qt ON qt.query_text_id = q.query_text_id
JOIN sys.query_store_plan p ON p.query_id = q.query_id
JOIN sys.query_store_runtime_stats rs ON rs.plan_id = p.plan_id
GROUP BY q.query_id, qt.query_sql_text
HAVING COUNT(DISTINCT p.plan_id) > 1
ORDER BY ratio DESC;