The Rambling DBA: Jonathan Kehayias : Digging into the SQL Plan Cache: Finding Missing Indexes

The Rambling DBA: Jonathan Kehayias : Digging into the SQL Plan Cache: Finding Missing Indexes



WITH XMLNAMESPACES
(DEFAULT 'http://schemas.microsoft.com/sqlserver/2004/07/showplan')

SELECT query_plan,
n.value('(@StatementText)[1]', 'VARCHAR(4000)') AS sql_text,
n.value('(//MissingIndexGroup/@Impact)[1]', 'FLOAT') AS impact,
DB_ID(REPLACE(REPLACE(n.value('(//MissingIndex/@Database)[1]', 'VARCHAR(128)'),'[',''),']','')) AS database_id,
OBJECT_ID(n.value('(//MissingIndex/@Database)[1]', 'VARCHAR(128)') + '.' +
n.value('(//MissingIndex/@Schema)[1]', 'VARCHAR(128)') + '.' +
n.value('(//MissingIndex/@Table)[1]', 'VARCHAR(128)')) AS OBJECT_ID,
n.value('(//MissingIndex/@Database)[1]', 'VARCHAR(128)') + '.' +
n.value('(//MissingIndex/@Schema)[1]', 'VARCHAR(128)') + '.' +
n.value('(//MissingIndex/@Table)[1]', 'VARCHAR(128)')
AS statement,
( SELECT DISTINCT c.value('(@Name)[1]', 'VARCHAR(128)') + ', '
FROM n.nodes('//ColumnGroup') AS t(cg)
CROSS APPLY cg.nodes('Column') AS r(c)
WHERE cg.value('(@Usage)[1]', 'VARCHAR(128)') = 'EQUALITY'
FOR XML PATH('')
) AS equality_columns,
( SELECT DISTINCT c.value('(@Name)[1]', 'VARCHAR(128)') + ', '
FROM n.nodes('//ColumnGroup') AS t(cg)
CROSS APPLY cg.nodes('Column') AS r(c)
WHERE cg.value('(@Usage)[1]', 'VARCHAR(128)') = 'INEQUALITY'
FOR XML PATH('')
) AS inequality_columns,
( SELECT DISTINCT c.value('(@Name)[1]', 'VARCHAR(128)') + ', '
FROM n.nodes('//ColumnGroup') AS t(cg)
CROSS APPLY cg.nodes('Column') AS r(c)
WHERE cg.value('(@Usage)[1]', 'VARCHAR(128)') = 'INCLUDE'
FOR XML PATH('')
) AS include_columns
INTO #MissingIndexInfo
FROM
(
SELECT query_plan
FROM (
SELECT DISTINCT plan_handle
FROM sys.dm_exec_query_stats WITH(NOLOCK)
) AS qs
OUTER APPLY sys.dm_exec_query_plan(qs.plan_handle) tp
WHERE tp.query_plan.exist('//MissingIndex')=1
) AS tab (query_plan)
CROSS APPLY query_plan.nodes('//StmtSimple') AS q(n)
WHERE n.exist('QueryPlan/MissingIndexes') = 1

-- Trim trailing comma from lists
UPDATE #MissingIndexInfo
SET equality_columns = LEFT(equality_columns,LEN(equality_columns)-1),
inequality_columns = LEFT(inequality_columns,LEN(inequality_columns)-1),
include_columns = LEFT(include_columns,LEN(include_columns)-1)

SELECT *
FROM #MissingIndexInfo

DROP TABLE #MissingIndexInfo