how to monitor a sql with subsecond elapsed time

Monitor a sql execution which lasted only for few seconds or even less... report the execution using dbms_sqltune

1) introduce the hint MONITOR in the desired sql, such that how short the execution time, the sql execution is monitored.

insert /*+ MONITOR */ into T1
select * from T1@to_r1;

2) use the dbms_sqltune to report the monitored sql.

SELECT DBMS_SQLTUNE.report_sql_monitor(sql_id=>'bfjf7tz62t1p5',type=>'TEXT',report_level => 'ALL')
from dual;

SQL Monitoring Report

SQL Text
------------------------------
insert /*+ MONITOR */ into T1 select * from T1@to_r1

Global Information
------------------------------
 Status              :  DONE
 Instance ID         :  1
 Session             :  SYSTEM (268:1203)
 SQL ID              :  bfjf7tz62t1p5
 SQL Execution ID    :  16777216
 Execution Started   :  12/02/2018 21:48:34
 First Refresh Time  :  12/02/2018 21:48:34
 Last Refresh Time   :  12/02/2018 21:48:37
 Duration            :  3s
 Module/Action       :  SQL*Plus/-
 Service             :  pdb2
 Program             :  sqlplus@db12c.oracle.com (TNS V1-V3)

Global Stats
===================================================================================
| Elapsed |   Cpu   |    IO    |  Other   | Buffer | Read | Read  | Write | Write |
| Time(s) | Time(s) | Waits(s) | Waits(s) |  Gets  | Reqs | Bytes | Reqs  | Bytes |
===================================================================================
|    3.10 |    1.20 |     0.02 |     1.88 |  20794 |   22 | 336KB |    18 |  10MB |
===================================================================================

SQL Plan Monitoring Details (Plan Hash Value=1788691278)
==============================================================================================================================================
| Id |         Operation         |        Name         |  Rows   | Cost |   Time    | Start  | Execs |   Rows   | Activity | Activity Detail |
|    |                           |                     | (Estim) |      | Active(s) | Active |       | (Actual) |   (%)    |   (# samples)   |
==============================================================================================================================================
|  0 | INSERT STATEMENT          |                     |         |      |         2 |     +2 |     1 |        0 |          |                   |
|  1 |   LOAD TABLE CONVENTIONAL |                     |         |      |         3 |     +1 |     1 |        0 |          |                   |
|  2 |    REMOTE                 | T1               |    186K | 3879 |         2 |     +2 |     1 |     186K |          |                   |
==============================================================================================================================================