最近碰到一个奇怪的问题，在生产和其他比较正式的环境中进行sql trace都没问题，但就是测试环境的数据库不知道怎么的, 设置sql_trace,开启诊断事件，dbms_system,dbms_monitor都试了，就是没有trace日志，我都怀疑是不是有些配置给禁用了。

查看基本的参数设置，没有发现什么问题。

NAME TYPE VALUEstatistics_level string TYPICALtimed_statistics boolean TRUE得到当前的session

SQL> select sid,serial# from v$session where sid=174;

SID SERIAL# 然后在另外一个session中开启trace8790 oracle 20ora_d003_TESTABP4发现这个进程是一个共享服务进程。再次查看session的情况，确实是。

SQL> select sid,serial#,server from v$session where sid=174;

SID SERIAL# SERVERSHARED看看当前的session server情况

SERVER COUNT(*)

SQL> select username,server from v$session group by username,server;

USERNAME SERVER

SQL> show parameter dispatchers

NAME TYPE VALUE

NAME TYPE VALUE查看监听器的情况，可以看到共享服务的分发器有5个，从D000到D004。

> lsnrctl service indlin224

LSNRCTL for Linux: Version 11.2.0.2.0 - Production on 28-APR-2014 14:22:01

Copyright (c) 1991, 2010, Oracle. All rights reserved.

Connecting to (address=(protocol=tcp)(host=indlin224)(port=1521))

Service "TESTABP4" has 1 instance(s).

SQL> select sid,serial#,server from v$session where sid=(select sid from v$mystat where rownum<2);SHAREDS002)D001)

SQL> select sid,serial#,server from v$session where sid=2947 and serial#=2427

SID SERIAL# SERVERNONE

How to Use PL/SQL Tracing with Multi-Threaded Server (MTS) (Doc ID 238935.1)

Oracle trace files are opened at the process level, not the session level.

If SQL_TRACE is turned on while running MTS, trace information for more than

By turning on SQL_TRACE in MTS mode, all user sessions that are currently

So, if performance tuning is being done and SQL_TRACE needs to be turned on, a