Dicas para um DBA Iniciante – Listando os principais Wait Types da instância

By Vitor Fava

Fala pessoas!!!!!

A dica de hoje é para ajudá-los a encontrar os principais wait types existentes em seu ambiente de banco de dados.

Esta consultar foi escrita pelo time do SQLSkills e é bem completa, pois já retorna também o link para a documentação escrita pelo Paul Randal e que explica minuciosamente cada um dos wait types encontrados e como resolvê-los.

WITH [Waits] 
     AS (SELECT [wait_type], 
                [wait_time_ms] / 1000.0                             AS [WaitS], 
                ( [wait_time_ms] - [signal_wait_time_ms] ) / 1000.0 AS 
                [ResourceS], 
                [signal_wait_time_ms] / 1000.0                      AS [SignalS] 
                , 
                [waiting_tasks_count] 
                AS [WaitCount], 
                100.0 * [wait_time_ms] / Sum ([wait_time_ms]) 
                                           OVER()                   AS 
                [Percentage], 
                Row_number() 
                  OVER( 
                    ORDER BY [wait_time_ms] DESC)                   AS [RowNum] 
         FROM   sys.dm_os_wait_stats 
         WHERE  [wait_type] NOT IN ( 
        N'BROKER_EVENTHANDLER', N'BROKER_RECEIVE_WAITFOR', 
        N'BROKER_TASK_STOP', 
                           N'BROKER_TO_FLUSH', 
                     N'BROKER_TRANSMITTER', N'CHECKPOINT_QUEUE', 
        N'CHKPT', 
                             N'CLR_AUTO_EVENT', 
                     N'CLR_MANUAL_EVENT', N'CLR_SEMAPHORE', 
                     -- Maybe uncomment these four if you have mirroring issues 
                     N'DBMIRROR_DBM_EVENT', N'DBMIRROR_EVENTS_QUEUE', 
                     N'DBMIRROR_WORKER_QUEUE', N'DBMIRRORING_CMD', 
                             N'DIRTY_PAGE_POLL', 
        N'DISPATCHER_QUEUE_SEMAPHORE', 
                     N'EXECSYNC', N'FSAGENT', 
        N'FT_IFTS_SCHEDULER_IDLE_WAIT', 
                             N'FT_IFTSHC_MUTEX', 
                     -- Maybe uncomment these six if you have AG issues 
                     N'HADR_CLUSAPI_CALL', 
        N'HADR_FILESTREAM_IOMGR_IOCOMPLETION' 
                             , 
        N'HADR_LOGCAPTURE_WAIT', 
        N'HADR_NOTIFICATION_DEQUEUE', 
                     N'HADR_TIMER_TASK', N'HADR_WORK_QUEUE', 
        N'KSOURCE_WAKEUP', 
                             N'LAZYWRITER_SLEEP' 
                                                , 
                     N'LOGMGR_QUEUE', N'MEMORY_ALLOCATION_EXT', 
                             N'ONDEMAND_TASK_QUEUE', 
        N'PREEMPTIVE_XE_GETTARGETSTATE', 
                     N'PWAIT_ALL_COMPONENTS_INITIALIZED', 
                             N'PWAIT_DIRECTLOGCONSUMER_GETNEXT', 
        N'QDS_PERSIST_TASK_MAIN_LOOP_SLEEP' 
        , 
                                                N'QDS_ASYNC_QUEUE', 
                     N'QDS_CLEANUP_STALE_QUERIES_TASK_MAIN_LOOP_SLEEP', 
        N'QDS_SHUTDOWN_QUEUE', 
        N'REDO_THREAD_PENDING_WORK', 
        N'REQUEST_FOR_DEADLOCK_SEARCH', 
                     N'RESOURCE_QUEUE', N'SERVER_IDLE_CHECK', 
        N'SLEEP_BPOOL_FLUSH', 
                                                N'SLEEP_DBSTARTUP', 
                     N'SLEEP_DCOMSTARTUP', N'SLEEP_MASTERDBREADY', 
        N'SLEEP_MASTERMDREADY', 
                                                N'SLEEP_MASTERUPGRADED', 
                     N'SLEEP_MSDBSTARTUP', N'SLEEP_SYSTEMTASK', 
        N'SLEEP_TASK', 
                                                N'SLEEP_TEMPDBSTARTUP', 
                     N'SNI_HTTP_ACCEPT', N'SP_SERVER_DIAGNOSTICS_SLEEP', 
        N'SQLTRACE_BUFFER_FLUSH', 
        N'SQLTRACE_INCREMENTAL_FLUSH_SLEEP', 
                     N'SQLTRACE_WAIT_ENTRIES', N'WAIT_FOR_RESULTS', 
        N'WAITFOR', 
                                                N'WAITFOR_TASKSHUTDOWN', 
                     N'WAIT_XTP_RECOVERY', N'WAIT_XTP_HOST_WAIT', 
        N'WAIT_XTP_OFFLINE_CKPT_NEW_LOG', 
                                                N'WAIT_XTP_CKPT_CLOSE', 
                     N'XE_DISPATCHER_JOIN', N'XE_DISPATCHER_WAIT', 
        N'XE_TIMER_EVENT' ) 
                AND [waiting_tasks_count] > 0) 
SELECT Max ([W1].[wait_type]) 
       AS 
       [WaitType], 
       Cast (Max ([W1].[waits]) AS DECIMAL (16, 2)) 
       AS [Wait_S], 
       Cast (Max ([W1].[resources]) AS DECIMAL (16, 2)) 
       AS [Resource_S], 
       Cast (Max ([W1].[signals]) AS DECIMAL (16, 2)) 
       AS [Signal_S], 
       Max ([W1].[waitcount]) 
       AS [WaitCount], 
       Cast (Max ([W1].[percentage]) AS DECIMAL (5, 2)) 
       AS [Percentage], 
       Cast (( Max ([W1].[waits]) / Max ([W1].[waitcount]) ) AS DECIMAL (16, 4)) 
       AS 
       [AvgWait_S], 
       Cast (( Max ([W1].[resources]) / Max ([W1].[waitcount]) ) AS 
             DECIMAL (16, 4)) AS 
       [AvgRes_S], 
       Cast (( Max ([W1].[signals]) / Max ([W1].[waitcount]) ) AS 
             DECIMAL (16, 4))   AS 
       [AvgSig_S], 
       Cast ('https://www.sqlskills.com/help/waits/' 
             + Max ([W1].[wait_type]) AS XML) 
       AS [Help/Info URL] 
FROM   [Waits] AS [W1] 
       INNER JOIN [Waits] AS [W2] 
               ON [W2].[rownum] <= [W1].[rownum] 
GROUP  BY [W1].[rownum] 
HAVING Sum ([W2].[percentage]) - Max([W1].[percentage]) < 95; -- percentage threshold 

Espero que gostem e não deixem de inscreverem-se no blog, no canal do youtube, no grupo de discussão SQLManiacs e em nosso grupo no TELEGRAM.

Grande abraço a todos.

Fonte: Vitor Fava