我的 XML 查询 CTE 有什么问题？

Question

基于 this answer，它有一个查询应该 return 来自扩展事件跟踪文件中的事件的 "call stack format" 结果集。

快速查询

SELECT CONVERT (XML, event_data) AS data
        FROM sys.fn_xe_file_target_read_file ('C:\Temp\test_trace*.xel', 'C:\Temp\test_trace*.xem', NULL, NULL)

returns 很多结果，显示正在记录事件，最终调用堆栈查询 returns 无结果。该查询基于以下 2 个 CTE：

WITH 
    CapturedResults AS
    ( SELECT data.value ( '(/event/@timestamp)[1]', 'DATETIME')                                        AS [TIME],
        data.value ( '(/event/data[@name=''cpu'']/value)[1]', 'INT')                                   AS [CPU (ms)],
        CONVERT (FLOAT, data.value ('(/event/data[@name=''duration'']/value)[1]', 'BIGINT')) / 1000000 AS [Duration (s)],
        data.value ( '(/event/action[@name=''sql_text'']/value)[1]', 'VARCHAR(MAX)')                   AS [SQL STATEMENT],
        CAST(data.value('(/event/action[@name="tsql_stack"]/value)[1]','varchar(MAX)') AS XML)         AS [stack_xml]       
    FROM (
        SELECT CONVERT (XML, event_data) AS data
        FROM sys.fn_xe_file_target_read_file ('C:\BradySqlTrace\test_trace*.xel', 'C:\BradySqlTrace\test_trace*.xem', NULL, NULL)) entries
    ),

    StackData AS
    ( SELECT frame_xml.value('(./@level)', 'int')      AS [frame_level],
        frame_xml.value('(./@handle)', 'varchar(MAX)') AS [sql_handle],
        frame_xml.value('(./@offsetStart)', 'int')     AS [offset_start],
        frame_xml.value('(./@offsetEnd)', 'int')       AS [offset_end]
    FROM CapturedResults CROSS APPLY stack_xml.nodes('//frame') N (frame_xml)
    )
SELECT * FROM StackData

当我从 CapturedResults select 时，我得到了预期的编号。行数，但是当我查询 StackData 时，我得到的结果为零。

有问题的 XML 节点应该生成 stack_xml 列，如下所示：

<event name="sp_statement_completed" package="sqlserver" timestamp="2017-05-08T12:37:15.132Z">
  ....
  <action name="tsql_stack" package="sqlserver">
    <value>
      <frames>
        <frame level="1" handle="0x03003D0084CC28352EF7C1006DA7000000000000000000000000000000000000000000000000000000000000" line="10" offsetStart="384" offsetEnd="466" />
        <frame level="2" handle="0x03003D00DAA5E13A62E99F006DA7000001000000000000000000000000000000000000000000000000000000" line="3" offsetStart="114" offsetEnd="-1" />
        <frame level="3" handle="0x01003D005CB2C92D10024E8F0000000000000000000000000000000000000000000000000000000000000000" line="2" offsetStart="4" offsetEnd="-1" />
      </frames>
    </value>
  </action>
</event>

我没有发布整个查询，因为我认为没有结果的第二个 CTE 是问题的开始，我应该首先解决这个问题。整个查询还有 return 个零结果。

Answer 1

您想使用 .query() 而不是 .value() 进行 xml->xml 转换。 .value() 用于 xml->scalar

WITH Events as
    (
      SELECT CONVERT (XML, event_data) AS data
      FROM sys.fn_xe_file_target_read_file ('C:\temp\test*.xel', 'C:\temp\test*.xem', NULL, NULL) 
    ),
    CapturedResults AS
    ( SELECT data.value ( '(/event/@timestamp)[1]', 'DATETIME')                                        AS [TIME],
        data.value ( '(/event/data[@name=''cpu'']/value)[1]', 'INT')                                   AS [CPU (ms)],
        CONVERT (FLOAT, data.value ('(/event/data[@name=''duration'']/value)[1]', 'BIGINT')) / 1000000 AS [Duration (s)],
        data.value ( '(/event/action[@name=''sql_text'']/value)[1]', 'VARCHAR(MAX)')                   AS [SQL STATEMENT],     
        data.query('/event/action[@name=''tsql_stack'']/value' )                                       AS [stack_xml]       
    FROM Events
    ),
    StackData AS
    ( SELECT frame_xml.value('(./@level)', 'int')      AS [frame_level],
        frame_xml.value('(./@handle)', 'varchar(MAX)') AS [sql_handle],
        frame_xml.value('(./@offsetStart)', 'int')     AS [offset_start],
        frame_xml.value('(./@offsetEnd)', 'int')       AS [offset_end]
    FROM CapturedResults CROSS APPLY stack_xml.nodes('//frame') N (frame_xml)
    )
SELECT * 
FROM StackData

大卫

我的 XML 查询 CTE 有什么问题？

What is wrong with my XML query CTE?

xml

sql

sql-server

extended-events

sql-server-2012