dmv-queries
A list of ready Dynamic Management View (DMV) queries for finding bottlenecks in your database layer
-- Finding Connection to Your Database
-- ------------------------------------------------------------------------------------------------
SELECT
database_id, -- SQL Server 2012 and after only
session_id,
status,
login_time,
cpu_time,
memory_usage,
reads,
writes,
logical_reads,
host_name,
program_name,
host_process_id,
client_interface_name,
login_name as database_login_name,
last_request_start_time
FROM sys.dm_exec_sessions
WHERE is_user_process = 1
ORDER BY cpu_time DESC;
-- Count of Connections by Login Name/Process (i.e. how many connections does an app have open)
-- ------------------------------------------------------------------------------------------------
SELECT
login_name,
host_name,
host_process_id,
COUNT(1) As LoginCount
FROM sys.dm_exec_sessions
WHERE is_user_process = 1
GROUP BY
login_name,
host_name,
host_process_id;
-- Finding statements running in the database right now (including if a statement is blocked by another)
-- -----------------------------------------------------------------------------------------------
SELECT
[DatabaseName] = db_name(rq.database_id),
s.session_id,
rq.status,
[SqlStatement] = SUBSTRING (qt.text,rq.statement_start_offset/2,
(CASE WHEN rq.statement_end_offset = -1 THEN LEN(CONVERT(NVARCHAR(MAX),
qt.text)) * 2 ELSE rq.statement_end_offset END - rq.statement_start_offset)/2),
[ClientHost] = s.host_name,
[ClientProgram] = s.program_name,
[ClientProcessId] = s.host_process_id,
[SqlLoginUser] = s.login_name,
[DurationInSeconds] = datediff(s,rq.start_time,getdate()),
rq.start_time,
rq.cpu_time,
rq.logical_reads,
rq.writes,
[ParentStatement] = qt.text,
p.query_plan,
rq.wait_type,
[BlockingSessionId] = bs.session_id,
[BlockingHostname] = bs.host_name,
[BlockingProgram] = bs.program_name,
[BlockingClientProcessId] = bs.host_process_id,
[BlockingSql] = SUBSTRING (bt.text, brq.statement_start_offset/2,
(CASE WHEN brq.statement_end_offset = -1 THEN LEN(CONVERT(NVARCHAR(MAX),
bt.text)) * 2 ELSE brq.statement_end_offset END - brq.statement_start_offset)/2)
FROM sys.dm_exec_sessions s
INNER JOIN sys.dm_exec_requests rq
ON s.session_id = rq.session_id
CROSS APPLY sys.dm_exec_sql_text(rq.sql_handle) as qt
OUTER APPLY sys.dm_exec_query_plan(rq.plan_handle) p
LEFT OUTER JOIN sys.dm_exec_sessions bs
ON rq.blocking_session_id = bs.session_id
LEFT OUTER JOIN sys.dm_exec_requests brq
ON rq.blocking_session_id = brq.session_id
OUTER APPLY sys.dm_exec_sql_text(brq.sql_handle) as bt
WHERE s.is_user_process =1
AND s.session_id <> @@spid
AND rq.database_id = DB_ID() -- Comment out to look at all databases
ORDER BY rq.start_time ASC;
-- Finding the most expensive statements in your database
-- ------------------------------------------------------------------------------------------------
SELECT TOP 20
DatabaseName = DB_NAME(CONVERT(int, epa.value)),
[Execution count] = qs.execution_count,
[CpuPerExecution] = total_worker_time / qs.execution_count ,
[TotalCPU] = total_worker_time,
[IOPerExecution] = (total_logical_reads + total_logical_writes) / qs.execution_count ,
[TotalIO] = (total_logical_reads + total_logical_writes) ,
[AverageElapsedTime] = total_elapsed_time / qs.execution_count,
[AverageTimeBlocked] = (total_elapsed_time - total_worker_time) / qs.execution_count,
[AverageRowsReturned] = total_rows / qs.execution_count,
[Query Text] = SUBSTRING(qt.text,qs.statement_start_offset/2 +1,
(CASE WHEN qs.statement_end_offset = -1
THEN LEN(CONVERT(nvarchar(max), qt.text)) * 2
ELSE qs.statement_end_offset end - qs.statement_start_offset)
/2),
[Parent Query] = qt.text,
[Execution Plan] = p.query_plan,
[Creation Time] = qs.creation_time,
[Last Execution Time] = qs.last_execution_time
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) as qt
OUTER APPLY sys.dm_exec_query_plan(qs.plan_handle) p
OUTER APPLY sys.dm_exec_plan_attributes(plan_handle) AS epa
WHERE epa.attribute = 'dbid'
AND epa.value = db_id()
ORDER BY [AverageElapsedTime] DESC; --Other column aliases can be used
-- Looking for Missing Indexes
-- ------------------------------------------------------------------------------------------------
SELECT
TableName = d.statement,
d.equality_columns,
d.inequality_columns,
d.included_columns,
s.user_scans,
s.user_seeks,
s.avg_total_user_cost,
s.avg_user_impact,
AverageCostSavings = ROUND(s.avg_total_user_cost * (s.avg_user_impact/100.0), 3),
TotalCostSavings = ROUND(s.avg_total_user_cost * (s.avg_user_impact/100.0) * (s.user_seeks + s.user_scans),3)
FROM sys.dm_db_missing_index_groups g
INNER JOIN sys.dm_db_missing_index_group_stats s
ON s.group_handle = g.index_group_handle
INNER JOIN sys.dm_db_missing_index_details d
ON d.index_handle = g.index_handle
WHERE d.database_id = db_id()
ORDER BY TableName, TotalCostSavings DESC;
-- Getting Stats on What Indexes are Used and What Indexes are Not
-- ------------------------------------------------------------------------------------------------
SELECT
[DatabaseName] = DB_Name(db_id()),
[TableName] = OBJECT_NAME(i.object_id),
[IndexName] = i.name,
[IndexType] = i.type_desc,
[TotalUsage] = IsNull(user_seeks, 0) + IsNull(user_scans, 0) + IsNull(user_lookups, 0),
[UserSeeks] = IsNull(user_seeks, 0),
[UserScans] = IsNull(user_scans, 0),
[UserLookups] = IsNull(user_lookups, 0),
[UserUpdates] = IsNull(user_updates, 0)
FROM sys.indexes i
INNER JOIN sys.objects o
ON i.object_id = o.object_id
LEFT OUTER JOIN sys.dm_db_index_usage_stats s
ON s.object_id = i.object_id
AND s.index_id = i.index_id
WHERE
(OBJECTPROPERTY(i.object_id, 'IsMsShipped') = 0)
ORDER BY [TableName], [IndexName];