This document discusses using Dynamic Management Views (DMVs) and Dynamic Management Functions (DMFs) in SQL Server to monitor and troubleshoot database performance issues. It begins with an introduction to DMVs/DMFs and their benefits. It then provides examples of DMVs and DMFs to monitor various aspects of the SQL Server architecture like execution plans, memory usage, I/O activity, and index usage. The document demonstrates some DMV/DMF queries and discusses how they can help identify issues like long-running queries, memory pressure, and missing indexes. It also provides additional DMV/DMF examples for common performance troubleshooting scenarios.

1. SUP303 - Trabalhando
com DMV e DMF
Fabricio Catae – Premier Field Engineer
Ioannis Xylaras – Premier Field Engineer
Microsoft Corporate

2. 01.
02.
03.
04.
05.
•
Introdução
•
Arquitetura do SQL Server
•
Storage Engine
•
Relational Engine
•
Adicionais

3. PREMIER FIELD ENGINEER
•
Suporte Global 24x7
•
Atendimento a contratos Premier Support
•
Especialista de produto
•
Tipos de Serviços
 Resolução de problemas
 Análise proativa de ambientes críticos
 Workshops e Transferência de conhecimento

4. MOTIVAÇÃO
•
Objetivo
 Utilizar DMV no dia a dia
•
Vantagens
 Nova ferramenta disponível no SQL 2005
 Revela detalhes sobre o funcionamento do servidor
 Executa tarefas que não são possíveis no SQL 2000

5. DYNAMIC MANAGEMENT OBJECTS
•
Dynamic Management Objects
 Dynamic Management Views (DMV)
 Dynamic Management Functions (DMF)
•
Características
 Somente para leitura
 Informação em memória
 Capturas instantâneas (snapshot)

6. CONSULTAS A DMV/DMF
•
Informações internas do SQL Server

7. TRABALHANDO COM DMV E DMF
•
Dynamic Management Objects
 Schema: sys
 Nome: dm_*
•
Exemplos:
SELECT * FROM sys.dm_exec_requests
SELECT * FROM sys.dm_exec_sessions
SELECT * FROM sys.dm_exec_connections
SELECT * FROM sys.dm_exec_sql_text(@h)

8. GRUPOS FUNCIONAIS
•
DMV/DMF estão organizados em categorias
 Common Language Runtime (CLR)
 Database Mirroring
 Database
 Execution
 Indexes
 I/O Operations
 Query Notifications
 Replication
 Service Broker
 SQL Server Operating System
 Transaction

9. DEMO
•
Select * from sys.system_objects
Where name like ‘dm_%’
•
Books Online 2005
 “Dynamic Management Objects”
 “sys.dm_exec_requests”

10. ARQUITETURA DO SQL SERVER
•
Storage Engine
 Infra-estrutura do SQL Server
 Comunicação com o Sistema Operacional
 Exemplos:
 Gerenciamento de Threads
 Gerenciamento de Memória
 Gerenciamento de I/O
•
Relational Engine
 Implementação da linguagem SQL
 Conceito de índices e estatísticas
 Exemplos:
 Compilação
 Otimização
 Execução da query

11. STORAGE ENGINE
•
Infra-estrutura do SQL Server
 Thread
 Memória
 I/O

12. THREADS
-
Threads
-
Worker Threads
-
Tasks
Task
Threads
Worker Threads

13. TASK / TAREFAS
•
Running, Runnable, Suspended
Task
Task
Task
Task
Task
Task
RUNNING
RUNNABLE
SUSPENDED

14. 100% CPU
•
sys.dm_os_tasks
 task_state
 RUNNING
 RUNNABLE
Worker Task
Worker Task
Worker Task
Worker Task

15. DEMOSNome:
Título:
•
Fabricio Catae
•
DMV’s

16. SUSPENDED
•
Tarefas Bloqueadas
 Disco
 Rede
 Linked Server
•
sys.dm_os_waiting_tasks
 session_id
 wait_type
 wait_duration_ms
 resource_description
 blocking_session_id

17. DISK I/O
•
Tarefas Bloqueadas
 Data Files: PAGEIOLATCH
 Log Files: WRITELOG
•
sys.dm_io_virtual_file_stats
 database_id
 file_id
 num_of_reads
 num_of_writes
 num_of_bytes_read
 num_of_bytes_written
NG
Auth
Sidep
AC
MM

18. DEMOSNome:
Título:
•
Fabricio Catae
•
DMV’s

19. GERENCIAMENTO DE MEMÓRIA
•
Módulo Reescrito para SQL 2005
 Memory Nodes
 Memory Clerks
 Cache e User Stores
 Page Allocators

20. DM_OS_MEMORY_*
•
dm_os_memory_clerks
•
User e Cache Stores
 dm_os_memory_cache_counters
 dm_os_memory_cache_hash_tables
 dm_os_memory_cache_clock
 dm_os_memory_cache_entries
•
Object Stores
 dm_os_memory_pools

21. DEMOSNome:
Título:
•
Fabricio Catae
•
DMV’s

22. RELATIONAL ENGINE
•
Execução de Query
•
Histórico de Execução
•
Utilização de Índices

23. EXECUÇÃO DE QUERY
-
session_id
-
sql_handle
- plan_handle
-
estatísticas
- cpu
- memória
- i/o
- duração
Session
Connection
Request
Request
Request

24. REQUEST DMV
•
DMV
 sys.dm_exec_connections
 sys.dm_exec_sessions
 sys.dm_exec_requests
•
DMF
 sys.dm_exec_connections( sql_handle )
 sys.dm_exec_connections( plan_handle )

25. DEMO
•
Cenário: 100% CPU
•
Select * from sys.dm_exec_connections
•
Select * from sys.dm_exec_sessions
•
Select * from sys.dm_exec_requests
•
Select * from sys.dm_exec_sql_text(@h)
•
Use substring
•
Select * from sys.dm_exec_requests
•
CROSS APPLY operator
•
Select * from sys.dm_exec_plan_handle(@h)
•
Save query plan to with sqlplan file extension

26. HISTÓRICO DE EXECUÇÃO
•
Após cada execução, essa DMV é atualizada
•
Colunas
 sql_handle
 plan_generation_num
 plan_handle
 last_execution
 execution_count
 total_worker_time
 total_physical_read/write
 total_logical_read/write
 total_elapsed_time

27. SQL_HANDLE
•
sys.dm_exec_sql_text( @handle )

28. NÚMERO DE EXECUÇÕES
•
Execution_count

29. TEMPO DE CPU UTILIZADO (MS)
•
Total_worker_time

30. TEMPO TOTAL GASTO (MS)
•
Total_elapsed_time

31. DM_EXEC_QUERY_STATS
•
Algumas queries não aparecem
 Extended Stored Procedures
 .NET Stored Procedures
 Comandos T-SQL (IF, WHILE, etc)
 Queries triviais
•
Existem situações que removem parte das estatísticas
 DBCC FREEPROCCACHE
 Memory Pressure

32. DEMO
•
Cenário: I/O intensive
•
Verificar que não há problemas
•
SELECT * FROM sys.dm_exec_requests
•
Listar todas as queries de sys.dm_exec_query_stats
•
Identificar os consumidores de CPU
•
Identificar os responsáveis pelos physical read
•
Calcular a média de leituras físicas
•
Utilizar sql_handle e plan_handle

33. ÍNDICES
•
Falta de índices adequados para queries
 sys.dm_db_missing_index_details
•
Utilização de Índices
 sys.dm_db_index_usage_stats

34. DEMOSNome:
Título:
•
Ioannis Xylaras
•
DMV’s

35. ADICIONAIS
•
Server level
 dm_exec_*
 Execution of user code and associated connections
 dm_os_*
 low level system (server-wide) info such as memory, locking &
scheduling
 dm_tran_*
 Transactions & isolation
 dm_io_*
 Input/Output on network and disks
 dm_db_*
 Databases and database objects
•
GRUPO DE DMV’S

36. ADICIONAIS
•
Component level
 dm_repl_*
 Replication
 dm_broker_*
 SQL Service Broker
 dm_fts_*
 Full Text Search
 dm_qn_*
 Query Notifications
•
GRUPO DE DMV’S

37. ADICIONAIS
•
MEMÓRIA ALOCADA
•
Você pode usar o sys.dm_os_memory_clerks DMV como
exemplo a seguir para identificar quanta memória o SQL
Server aloca através do mecanismo do AWE.
•
Select
sum(awe_allocated_kb) / 1024 as [AWE allocated, Mb] from
sys.dm_os_memory_clerks
•
•
CENÁRIO DE PERFORMANCE

38. ADICIONAIS
•
Query plan ineficiente
•
A query sys.dm_exec_query_stats é um eficiente caminho
para determinar qual query está usando a maior CPU
cumulativa.
•
Select
•
highest_cpu_queries.plan_handle,
•
highest_cpu_queries.total_worker_time,
•
q.dbid, q.objectid, q.number, q.encrypted, q.[text]
•
from
•
(select top 50 qs.plan_handle, qs.total_worker_time
•
from sys.dm_exec_query_statssys.dm_exec_query_stats qs
•
order by qs.total_worker_time desc) as highest_cpu_queries
•
cross apply sys.dm_exec_sql_text(plan_handle) as q
•
order by highest_cpu_queries.total_worker_time desc
•
CENÁRIO DE PERFORMANCE

39. ADICIONAIS
•
Top CPUs procs & batches
Select top 50
•
sum(qs.total_worker_time) as total_cpu_time,
•
sum(qs.execution_count) as total_execution_count,
•
count(*) as '#_statements',
•
qt.dbid, qt.objectid, qs.sql_handle,
•
qt.[text] from sys.dm_exec_query_stats as qs
•
cross apply sys.dm_exec_sql_text (qs.sql_handle) as qt
•
group by qt.dbid,qt.objectid, qs.sql_handle,qt.[text]
•
order by sum(qs.total_worker_time) desc,qs.sql_handle
•
CENÁRIO DE PERFORMANCE

40. ADICIONAIS
•
CPU – O que está executando em paralelo?
•
Paralelismo é bom para DW, não para OLTP
Select r.session_id,
r.request_id,
max(isnull(exec_context_id, 0)) as number_of_workers,
r.sql_handle,
r.statement_start_offset,
r.statement_end_offset,
r.plan_handle
from sys.dm_exec_requestssys.dm_exec_requests r
join sys.dm_os_tasks t on r.session_id = t.session_id
join sys.dm_exec_sessions s on r.session_id = s.session_id
where s.is_user_process = 0x1
group by r.session_id, r.request_id, r.sql_handle, r.plan_handle,
r.statement_start_offset, r.statement_end_offset
having max(isnull(exec_context_id, 0)) > 0
•
CENÁRIO DE PERFORMANCE

41. ADICIONAIS
•
Pressão CPU : Recompilação
•
Select top 25
•
sql_text.text,
•
sql_handle,
•
plan_generation_num,
•
execution_count,
•
dbid,
•
objectid
•
from sys.dm_exec_query_statssys.dm_exec_query_stats a
•
Cross apply sys.dm_exec_sql_text(sql_handle) as sql_text
•
where plan_generation_num >1
•
order by plan_generation_num desc
•
CENÁRIO DE PERFORMANCE

42. ADICIONAIS
•
Memória: Top memory por objeto & índice
•
CENÁRIO DE PERFORMANCE
Select b.database_id
,p.object_id
,object_name(p.object_id) as objname
,p.index_id
,buffer_count=count(*)
from sys.allocation_units a,
sys.dm_os_buffer_descriptorssys.dm_os_buffer_descriptors b,
sys.partitions p
where a.allocation_unit_id =
b.allocation_unit_id
and a.container_id = p.hobt_id
group by b.database_id,p.object_id,
p.index_id
order by buffer_count desc

43. ADICIONAIS
•
Top IOs por statement
•
SELECT TOP 50
•
(qs.total_logical_reads + qs.total_logical_writes) /qs.execution_count
•
as [Avg IO],
•
substring (qt.text,qs.statement_start_offset/2, (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)
•
as query_text,
•
qt.dbid,
•
qt.objectid
•
FROM sys.dm_exec_query_statssys.dm_exec_query_stats qs
•
cross apply sys.dm_exec_sql_text (qs.sql_handle) as qt
•
ORDER BY
•
[Avg IO] DESC
•
CENÁRIO DE PERFORMANCE

44. ADICIONAIS
•
Visualizando a utilização dos índices das tabelas
•
Select so.name AS 'Table Name', si.name AS 'index Name',
si.type_desc AS 'Index Type', si.index_id AS 'Index ID',
us.user_seeks, us.user_scans, us.system_seeks, us.system_scans
FROM sys.dm_db_index_usage_statssys.dm_db_index_usage_stats us
INNER JOIN sys.objects so
ON us.object_id = so.object_id
INNER JOIN sys.indexes si
ON so.object_id = si.object_id
WHERE so.type = 'U'
•
CENÁRIO DE PERFORMANCE

45. ADICIONAIS
•
Visualizando Índices não atualmente utilizados
Select so.name AS 'Table Name', si.name AS 'index Name',
si.type_desc AS 'Index Type', si.index_id AS 'Index ID',
•
us.user_seeks, us.user_scans, us.system_seeks, us.system_scans,
us.user_lookups, us.system_lookups,us.user_updates,
•
us.system_updates
•
--other columns are available
•
FROM sys.dm_db_index_usage_statssys.dm_db_index_usage_stats us
•
INNER JOIN sys.objects so ON us.object_id = so.object_id
•
INNER JOIN sys.indexes si ON so.object_id = si.object_id
•
WHERE so.type = 'U' AND us.user_seeks = 0
•
AND us.user_scans = 0 AND us.system_seeks = 0
•
AND us.system_scans = 0
•
CENÁRIO DE PERFORMANCE

46. PRÓXIMAS PALESTRAS

47. PRÓXIMAS
PALESTRAS
Palestra 1:
Palestra 2:
Palestra 3:
•
SUP304 Otimizando os Subsistemas
de Discos para o Microsoft Exchange
Server
30/11/2006 15:30 - 16:45
•
SUP305 Processo de Migração para
ISA Server 2006
30/11/2006 17:00 - 18:15
•
Ask the Experts

48. LINKS ÚTEIS
SQL Server 2005 System Views Online
http://download.microsoft.com/download/0/d/f/0df
e488e-a335-4480-8a8a-
b405e32f4368/SQL2005_Sys_Views.pdf
Troubleshooting Performance
Problems in SQL 2005
http://www.microsoft.com/technet/prodtechn
ol/sql/2005/tsprfprb.mspx
SQL Server 2005 Books Online
http://www.microsoft.com/technet/prodtechn
ol/sql/2005/downloads/books.mspx
Dynamic Management Views and
Functions
http://msdn2.microsoft.com/en-
us/library/ms188754.aspx

49. LINKS ÚTEIS
Technet Brasil
http://www.microsoft.com/brasil/technet
http://www.microsoft.com/brasil/technet/comunid
ade/default.mspx
http://forums.microsoft.com/technet-br
Certificações Microsoft
http://www.microsoft.com/brasil/certifique
http://www.microsoft.com/learning
Slava Oks Blog
http://blogs.msdn.com/slavao
Microsoft Most Valuable Professional
http://mvp.support.microsoft.com/

50. PERGUNTAS E RESPOSTAS
•
Fabricio Catae
Ioannis Xylaras
••
Microsoft Corporate