Find queries using index

Find queries using index. Initially used to detect queries that were using eager spooling

can be used for index optimization as well

SELECT
querystats.plan_handle,
querystats.query_hash,
SUBSTRING(sqltext.text, (querystats.statement_start_offset / 2) + 1,
(CASE querystats.statement_end_offset
WHEN -1 THEN DATALENGTH(sqltext.text)
ELSE querystats.statement_end_offset
END - querystats.statement_start_offset) / 2 + 1) AS sqltext,
querystats.execution_count,
querystats.total_logical_reads,
querystats.total_logical_writes,
querystats.creation_time,
querystats.last_execution_time,
CAST(query_plan AS xml) as plan_xml
FROM sys.dm_exec_query_stats as querystats
CROSS APPLY sys.dm_exec_text_query_plan
(querystats.plan_handle, querystats.statement_start_offset, querystats.statement_end_offset)
as textplan
CROSS APPLY sys.dm_exec_sql_text(querystats.sql_handle) AS sqltext
WHERE
textplan.query_plan like '%missing%'
ORDER BY querystats.last_execution_time DESC
OPTION (RECOMPILE);
GO

further reading

https://littlekendra.com/2017/01/24/how-to-find-queries-using-an-index-and-queries-using-index-hints/ - How to Find Queries Using an Index
https://sqlperformance.com/2013/02/t-sql-queries/halloween-problem-part-1 - The Halloween Problem
https://www.red-gate.com/simple-talk/sql/learn-sql-server/operator-of-the-week-spools-eager-spool/ - Operator of the Week – Spools, Eager Spool
https://www.itprotoday.com/sql-server/divide-and-conquer-halloween - Divide and Conquer Halloween