Extended Event force order of sys.fn_xe_file_target_read_file() DMF results

Question

Microsoft SQL Server 2008 R2 (SP2) - 10.50.4000.0 (X64) Jun 28 2012 08:36:30 Copyright (c) Microsoft Corporation Enterprise Edition (64-bit) on Windows NT 6.1 (Build 7601: Service Pack 1)

Is there a way to guarantee the order of results when reading an Extended event .xel log file using the sys.fn_xe_file_target_read_file() DMF? Ideally I would like to number the records 1..X based on the order in which they were inserted into the .xel file.

I need to poll the file target multiple times and insert new records into a table. If I could guarantee the order of results then I could add the Meta data column "Entry Number", and use this column to avoid inserting the same records over multiple executions i.e.

SELECT  entries.EntryNumber
        ,entries.file_name
        ,entries.data
        ,entries.file_offset
FROM    (
        SELECT  ROW_NUMBER() OVER (ORDER BY <GUARANTEE ORDERING BASED ON ORDER OF INSERTION>) AS EntryNumber,
                file_name,
                CONVERT (XML, event_data) AS data
                ,file_offset
        FROM    sys.fn_xe_file_target_read_file ('C:\ExEvent_0_123456789.xel', 'C:\ExEvent_0_123456789.xem', NULL, NULL)
                ) entries
WHERE   NOT EXISTS 
        (
        SELECT  1
        FROM    dbo.ExEventLog d
        WHERE   entries.EntryNumber = d.EntryNumber                         
        )

If this is not possible, can I guarantee that all records with the same 'file_offset' value are loaded into the .xel file in one single batch? For example if I query the .xel file for all records with a 'file_offset' of 123, can I guarantee that no additional records with a ‘file_offset’ of 123 will be loaded subsequently?

This is based on creating the extended event WITH MAX_DISPATCH_LATENCY = 1 SECONDS and polling the .xel file every 60 seconds.

I don't feel comfortable using the @initial_file_name and @initial_offset paramters because of this bug / feature : http://connect.microsoft.com/SQLServer/feedback/details/714286/sys-fn-file-target-read-file-reads-incorrect-files-when-offset-reading#details

Answer 1

You can use the timestamp attribute from the root node in event_data.

SELECT  entries.EntryNumber
        ,entries.file_name
        ,entries.data
        ,entries.file_offset
FROM    (
        SELECT  ROW_NUMBER() OVER (ORDER BY X.data.value('(/event/@timestamp)[1]', 'datetime')) AS EntryNumber
                ,file_name
                ,X.data
                ,file_offset
        FROM    sys.fn_xe_file_target_read_file ('C:\ExEvent_0_123456789.xel', 'C:\ExEvent_0_123456789.xem', NULL, NULL)
          CROSS APPLY (SELECT CONVERT(XML, event_data) AS data) AS X
        ) entries

Answer 2

If you want to GUARANTEE ORDERING BASED ON ORDER OF INSERTION, use a temp table with identity(int, 1, 1) column:

SELECT  
        file_name
        ,CONVERT (XML, event_data) AS data
        ,file_offset
        ,identity(int, 1, 1) AS EntryNumber
into #tmp
FROM    sys.fn_xe_file_target_read_file ('C:\ExEvent_0_123456789.xel', 'C:\ExEvent_0_123456789.xem', NULL, NULL)

SELECT  entries.EntryNumber
    ,entries.file_name
    ,entries.data
    ,entries.file_offset
FROM #tpm entries
WHERE   NOT EXISTS 
    (
    SELECT  1
    FROM    dbo.ExEventLog d
    WHERE   entries.EntryNumber = d.EntryNumber                         
    )

DROP TABLE #tmp

Row_Number is not meant to do that.