创建扩展事件会话：将慢查询捕获到文件并读取

命令

SET QUOTED_IDENTIFIER ON;
CREATE EVENT SESSION [dba_long_queries] ON SERVER
ADD EVENT sqlserver.sql_statement_completed (
    ACTION (sqlserver.client_app_name, sqlserver.client_hostname, sqlserver.database_name,
            sqlserver.session_id, sqlserver.sql_text, sqlserver.username, sqlserver.query_hash)
    WHERE (duration >= 1000000 AND sqlserver.is_system = 0)),   -- 1 s (microseconds)
ADD EVENT sqlserver.rpc_completed (
    ACTION (sqlserver.client_app_name, sqlserver.client_hostname, sqlserver.database_name,
            sqlserver.session_id, sqlserver.sql_text, sqlserver.username, sqlserver.query_hash)
    WHERE (duration >= 1000000 AND sqlserver.is_system = 0))
ADD TARGET package0.event_file (SET filename = N'D:\XE\dba_long_queries.xel',
                                    max_file_size = 256, max_rollover_files = 4)
WITH (MAX_MEMORY = 8 MB, EVENT_RETENTION_MODE = ALLOW_SINGLE_EVENT_LOSS,
      MAX_DISPATCH_LATENCY = 15 SECONDS, STARTUP_STATE = OFF);

ALTER EVENT SESSION [dba_long_queries] ON SERVER STATE = START;

-- Read:
SELECT x.value('(event/@name)[1]', 'sysname')                                AS event_name,
       x.value('(event/@timestamp)[1]', 'datetime2')                         AS utc_time,
       x.value('(event/data[@name="duration"]/value)[1]', 'bigint') / 1000   AS duration_ms,
       x.value('(event/data[@name="cpu_time"]/value)[1]', 'bigint') / 1000   AS cpu_ms,
       x.value('(event/data[@name="logical_reads"]/value)[1]', 'bigint')     AS logical_reads,
       x.value('(event/action[@name="database_name"]/value)[1]', 'sysname')  AS db,
       x.value('(event/action[@name="client_app_name"]/value)[1]', 'nvarchar(256)') AS app,
       x.value('(event/action[@name="sql_text"]/value)[1]', 'nvarchar(max)') AS sql_text
FROM  (SELECT CAST(event_data AS XML) AS x
       FROM sys.fn_xe_file_target_read_file(N'D:\XE\dba_long_queries*.xel', NULL, NULL, NULL)) t
ORDER BY duration_ms DESC;

-- When done:
-- ALTER EVENT SESSION [dba_long_queries] ON SERVER STATE = STOP;
-- DROP EVENT SESSION [dba_long_queries] ON SERVER;

作用

创建一个轻量级扩展事件会话，把超过 1 秒的语句和 RPC 调用连同应用、主机、用户、数据库和 SQL 文本写入磁盘；用 T-SQL 将 .xel 文件转换为行。

适用场景

用于间歇性变慢的投诉、需要 Query Store 不显示的客户端信息（应用/主机）时，以及替代 SQL Trace/Profiler。

注意

阈值过低（如 0）会很快写满文件，并在繁忙服务器上增加开销；在 WHERE 谓词中过滤，而不是事后过滤。大量数据时 sql_text action 开销较大。SQL Server 服务账户必须对该文件夹有写权限。duration 和 cpu_time 以微秒为单位。用完后停止/删除会话；STARTUP_STATE = OFF 时重启后不会自动启动。