2016-10-11

SQL Trace

SQL Trace, even it's a quite old feature, still loved by lot of database administrators due to its simplicity of creation. Rather than writing a sql script to call sp_trace_xxx system stored procedures, it can be created by using SQL Profiler to export a trace definition script, as below steps:

1. Open SQL Server Profiler;
2. Create a new trace;
3. Select a trace template, pick the required events, columns, and set filters as you wish;
4. Start the trace;
5. Stop the trace;
6. Click "File" menu -> "Export" -> "Script Trace Definition" -> "For SQL Server 2005 - 2014..."
7. Save the exported sql file.
The trace definition sql script will be something like below:
8. Replace the text "InsertFileNameHere" with a filename prefixed by a path, e.g., c:\MyFolder\MyTrace. The .trc extension will be appended to the filename automatically;
9. If you wanna use rollover files on the .trc trace output, change the second parameter value of sp_trace_create from 0 to 2. The default value of max_file_size is 5 MB;
10. Noted that trace definitions will be automatically removed in the case of SQL Server restart, so if you wanna the same trace survives server restart, you can create a stored procedure in the master database, which wrap up the above trace definition script, then execute sp_procoption to set that stored procedure for automatic execution every time SQL Server is started. You can check which stored procedure(s) in master database will be auto-executed by the following query using sysadmin login to run:
USE master
SELECT [name]
FROM sysobjects
WHERE type = 'P'
  AND OBJECTPROPERTY(id, 'ExecIsStartUp') = 1; 

11. Execute the trace definition script to create and start the trace.

After the trace is created, you can check the properties of a trace, including path of the output .trc file, is rollover, events, columns, and filters, by below queries:
-- view created traces
SELECT * FROM sys.traces
-- view trace events & columns
SELECT
     e.name AS Event_Name,
     c.name AS Column_Name
FROM fn_trace_geteventinfo(3) ei    -- replace the fn param value with the Trace ID u wanna check
JOIN sys.trace_events e ON ei.eventid = e.trace_event_id
JOIN sys.trace_columns c ON ei.columnid = c.trace_column_id
-- view trace filters
SELECT
     columnid,
    c.name AS Column_Name,
     logical_operator,
     comparison_operator,
     value
FROM fn_trace_getfilterinfo(3) fi    -- replace the fn param value with the Trace ID u wanna check
JOIN sys.trace_columns c ON fi.columnid = c.trace_column_id 


To see the trace output, you can open the .trc files by SQL Profiler, or you can use fn_trace_gettable which returns the content of one or more trace files in tabular form, e.g.
-- view trace output as table
SELECT *
FROM fn_trace_gettable('H:\SYSADMIN_AUDIT\sysadmin_audit_168.trc', default)    -- 1st param:initial file; 2nd param:no. of rollover files to be read (default=until last file) 



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