• Artigo

Tipo de coletor Atividade de Consulta

O tipo de coletor de Atividade de Consulta é um tipo de coletor personalizado usado pelo conjunto de coleta de Estatísticas da Consulta, um dos conjuntos de coleta de dados predefinidos do sistema.

Esse tipo de coletor é usado para coletar estatísticas de consulta e informações de atividade de consulta juntamente com o plano e o texto de consultas que atendem a critérios predefinidos. Se você criar seu próprio conjunto de coleta usando esse tipo de coletor, ele coletará as mesmas informações que o conjunto de coleta Estatísticas da Consulta. Portanto, é recomendável que você use o conjunto de coleta Estatísticas da Consulta predefinido.

Arquitetura e processamento

O tipo de coletor de Atividade de Consulta consiste nos seguintes elementos:

  • Um esquema de parâmetros de entrada (interno)

  • Um pacote do SSIS para coleta de dados (QueryActivityCollect.dtsx)

  • Um pacote do SSIS para carregamento de dados (QueryActivityUpload.dtsx)

Além disso, esse tipo de coletor usa transformações ou tarefas personalizadas para analisar e selecionar dados para armazenamento no data warehouse de gerenciamento.

O tipo de coletor de Atividade de Consulta executa as seguintes operações:

  • Ele coleta exemplos de dm_exec_requests, dm_exec_sessions e seleciona outras exibições de gerenciamento dinâmico relacionadas. Isto é implementado como uma única consulta unida. A coleta de dados ocorre com a frequência especificada para o item de coleta.

  • Ele coleta instantâneos da exibição de gerenciamento dinâmico dm_exec_query_stats com uma frequência igual à frequência de carregamento do conjunto de coleta. Por padrão, o conjunto de coleta Estatísticas de Consulta tem uma frequência de carregamento de 15 minutos.

Fase de coleta

A tabela a seguir mostra a consulta usada durante a fase de coleta. Essa consulta é definida no pacote do SSIS QueryActivityCollect.dtsx.

Frequência da coleta

10 segundos

Consulta

 
SET NOCOUNT ON
-- Get the collection time as UTC time
DECLARE @collection_time datetime
SET @collection_time = GETDATE()
SELECT
CONVERT(int, ROW_NUMBER() OVER (ORDER BY sess.session_id, ISNULL (req.request_id, -1), ISNULL (tasks.exec_context_id, -1)) ) AS row_id,
-- IDs and Blocking IDs
sess.session_id, 
ISNULL (req.request_id, -1) AS request_id, 
ISNULL (tasks.exec_context_id, -1) AS exec_context_id, 
ISNULL (req.blocking_session_id, 0) AS blocking_session_id,
CONVERT (bit, CASE 
                WHEN EXISTS (SELECT TOP 1 session_id FROM sys.dm_exec_requests bl WHERE bl.blocking_session_id = req.session_id) THEN 1
                ELSE 0
              END) AS is_blocking,
ISNULL (waits.blocking_exec_context_id, 0) AS blocking_exec_context_id, 
tasks.scheduler_id, 
DB_NAME(req.database_id) as database_name, 
req.[user_id], 
-- State information
LEFT (tasks.task_state, 10) AS task_state, 
LEFT (req.status, 15) AS request_status, 
LEFT (sess.status, 15) AS session_status,
req.executing_managed_code, 
-- Session information
sess.login_time, 
sess.is_user_process, 
LEFT (ISNULL (sess.[host_name], ''), 20) AS [host_name], 
LEFT (ISNULL (sess.[program_name], ''), 50) AS [program_name], 
LEFT (ISNULL (sess.login_name, ''), 30) AS login_name, 
-- Waits information
LEFT (ISNULL (req.wait_type, ''), 45) AS wait_type, 
LEFT (ISNULL (req.last_wait_type, ''), 45) AS last_wait_type, 
ISNULL (waits.wait_duration_ms, 0) AS wait_duration_ms, 
LEFT (ISNULL (req.wait_resource, ''), 50) AS wait_resource, 
LEFT (ISNULL (waits.resource_description, ''), 140) AS resource_description,
-- Transaction information
req.transaction_id, 
ISNULL(req.open_transaction_count, 0) AS open_transaction_count,
COALESCE(req.transaction_isolation_level, sess.transaction_isolation_level) AS transaction_isolation_level,
-- Request stats
req.cpu_time AS request_cpu_time, 
req.logical_reads AS request_logical_reads, 
req.reads AS request_reads, 
req.writes AS request_writes, 
req.total_elapsed_time AS request_total_elapsed_time, 
req.start_time AS request_start_time, 
-- Session stats
sess.memory_usage, 
sess.cpu_time AS session_cpu_time, 
sess.reads AS session_reads, 
sess.writes AS session_writes, 
sess.logical_reads AS session_logical_reads, 
sess.total_scheduled_time AS session_total_scheduled_time, 
sess.total_elapsed_time AS session_total_elapsed_time, 
sess.last_request_start_time, 
sess.last_request_end_time, 
req.open_resultset_count AS open_resultsets, 
sess.row_count AS session_row_count, 
sess.prev_error, 
tasks.pending_io_count, 
-- Text/Plan handles
ISNULL (req.command, 'AWAITING COMMAND') AS command,  
req.plan_handle, 
req.sql_handle, 
req.statement_start_offset, 
req.statement_end_offset,
@collection_time AS collection_time
FROM sys.dm_exec_sessions sess 
LEFT OUTER MERGE JOIN sys.dm_exec_requests req  ON sess.session_id = req.session_id
LEFT OUTER MERGE JOIN sys.dm_os_tasks tasks ON tasks.session_id = sess.session_id AND tasks.request_id = req.request_id AND tasks.task_address = req.task_address
LEFT OUTER MERGE JOIN sys.dm_os_waiting_tasks waits ON waits.session_id = sess.session_id AND waits.waiting_task_address = req.task_address
WHERE 
    sess.session_id <> @@SPID
    AND
    (
        (req.session_id IS NOT NULL AND (sess.is_user_process = 1 OR req.status COLLATE Latin1_General_BIN NOT IN ('background', 'sleeping')))-- active request
            OR 
        (sess.session_id IN (SELECT DISTINCT blocking_session_id FROM sys.dm_exec_requests WHERE blocking_session_id != 0))            -- not active, but head blocker
    )
OPTION (FORCE ORDER)

Fase de carregamento

Durante a fase de carregamento, os dados coletados são analisados para determinar quais dados serão salvos no data warehouse de gerenciamento. Essa análise determina um conjunto de estatísticas, planos e texto da consulta que precisam ser salvos.

Um elemento principal é um algoritmo que seleciona as consultas e os planos de consulta a serem salvos no data warehouse. Esse algoritmo funciona da seguinte maneira:

  1. Coleta um instantâneo de sys.dm_exec_query_stats. Esse instantâneo é coletado na mesma frequência do carregamento do conjunto de coleta. (Por padrão, 15 minutos).

  2. Recupera o instantâneo mais recente (de 15 minutos atrás) para comparação com o novo instantâneo. O instantâneo mais recente é armazenado em cache localmente e não precisa ser recuperado do data warehouse de gerenciamento.

  3. Seleciona as três principais consultas de cada instantâneo usando a métrica a seguir:

    • Tempo decorrido

    • Tempo de trabalho

    • Leituras lógicas

    • Gravações lógicas

    • Leituras físicas

    • Contagem de execuções

    Esse processo fornece 6 x 3 sql_handles e plan_handles.

  4. Identifica os sql_handles e plan_handles exclusivos.

  5. Cruza esse resultado com os sql_handles e plan_handles armazenados no data warehouse.

    Para sql_handles e plan_handles novos, obtém o plano e o texto do servidor. Se o plano ou o texto não for localizado (talvez já tenha sido removido do cache local), armazena os identificadores no data warehouse de gerenciamento.

  6. Para cada texto sql_handle coletado, normaliza o texto (por exemplo, remove parâmetros e literais) e calcula o valor de hash exclusivo do texto normalizado. Armazena o texto normalizado, o valor de hash e o mapeamento para o sql_handle original no data warehouse de gerenciamento.

A tabela a seguir mostra a consulta usada para obter os instantâneos e analisar e, em seguida, carregar os dados no data warehouse de gerenciamento. Essa consulta é definida no pacote do SSIS QueryActivityUpload.dtsx.

Consulta

 
SET NOCOUNT ON
DECLARE @p1 datetime
SET @p1 = GETDATE()
SELECT 
    [sql_handle],
    statement_start_offset,
    statement_end_offset,
    -- Use ISNULL here and in other columns to handle in-progress queries that are not yet in sys.dm_exec_query_stats.  
    -- These values only come from sys.dm_exec_query_stats. If the plan does not show up in sys.dm_exec_query_stats 
    -- (first execution of a still-in-progress query, visible in sys.dm_exec_requests), these values will be NULL. 
    MAX (plan_generation_num) AS plan_generation_num,
    plan_handle,
    MIN (creation_time) AS creation_time, 
    MAX (last_execution_time) AS last_execution_time,
    SUM (execution_count) AS execution_count,
    SUM (total_worker_time) AS total_worker_time,
    MIN (min_worker_time) AS min_worker_time,           -- NULLable
    MAX (max_worker_time) AS max_worker_time,
    SUM (total_physical_reads) AS total_physical_reads,
    MIN (min_physical_reads) AS min_physical_reads,     -- NULLable
    MAX (max_physical_reads) AS max_physical_reads,
    SUM (total_logical_writes) AS total_logical_writes,
    MIN (min_logical_writes) AS min_logical_writes,     -- NULLable
    MAX (max_logical_writes) AS max_logical_writes,
    SUM (total_logical_reads) AS total_logical_reads,
    MIN (min_logical_reads) AS min_logical_reads,       -- NULLable
    MAX (max_logical_reads) AS max_logical_reads,
    SUM (total_clr_time) AS total_clr_time,
    MIN (min_clr_time) AS min_clr_time,                 -- NULLable
    MAX (max_clr_time) AS max_clr_time,
    SUM (total_elapsed_time) AS total_elapsed_time,
    MIN (min_elapsed_time) AS min_elapsed_time,         -- NULLable
    MAX (max_elapsed_time) AS max_elapsed_time,
    @p1 AS collection_time
FROM
(
    SELECT  
        [sql_handle],
        statement_start_offset,
        statement_end_offset,
        plan_generation_num,
        plan_handle,
        creation_time,
        last_execution_time,
        execution_count,
        total_worker_time,
        min_worker_time,
        max_worker_time,
        total_physical_reads,
        min_physical_reads,
        max_physical_reads,
        total_logical_writes,
        min_logical_writes,
        max_logical_writes,
        total_logical_reads,
        min_logical_reads,
        max_logical_reads,
        total_clr_time,
        min_clr_time,
        max_clr_time,
        total_elapsed_time,
        min_elapsed_time,
        max_elapsed_time 
    FROM sys.dm_exec_query_stats AS q
    UNION ALL 
    SELECT 
        r.[sql_handle],
        r.statement_start_offset,
        r.statement_end_offset,
        ISNULL (qs.plan_generation_num, 0) AS plan_generation_num,
        r.plan_handle,
        ISNULL (qs.creation_time, r.start_time) AS creation_time,
        r.start_time AS last_execution_time,
        1 AS execution_count,
        r.cpu_time AS total_worker_time,
        qs.min_worker_time,     -- min should not be influenced by in-progress queries
        r.cpu_time AS max_worker_time,
        r.reads AS total_physical_reads,
        qs.min_physical_reads,  -- min should not be influenced by in-progress queries
        r.reads AS max_physical_reads,
        r.writes AS total_logical_writes,
        qs.min_logical_writes,  -- min should not be influenced by in-progress queries
        r.writes AS max_logical_writes,
        r.logical_reads AS total_logical_reads,
        qs.min_logical_reads,   -- min should not be influenced by in-progress queries
        r.logical_reads AS max_logical_reads,
        qs.total_clr_time,      -- CLR time is not available in dm_exec_requests
        qs.min_clr_time,        -- CLR time is not available in dm_exec_requests
        qs.max_clr_time,        -- CLR time is not available in dm_exec_requests
        r.total_elapsed_time AS total_elapsed_time,
        qs.min_elapsed_time,    -- min should not be influenced by in-progress queries
        r.total_elapsed_time AS max_elapsed_time
    FROM sys.dm_exec_requests AS r 
    LEFT OUTER JOIN sys.dm_exec_query_stats AS qs ON r.plan_handle = qs.plan_handle AND r.statement_start_offset = qs.statement_start_offset 
        AND r.statement_end_offset = qs.statement_end_offset 
    WHERE r.sql_handle IS NOT NULL 
) AS query_stats 
OUTER APPLY sys.dm_exec_sql_text (sql_handle) AS sql
GROUP BY [sql_handle], plan_handle, statement_start_offset, statement_end_offset 
ORDER BY [sql_handle], plan_handle, statement_start_offset, statement_end_offset

Saída da consulta

snapshots.query_stats, snapshots.notable_query_text e snapshots.notable_query_plan