在客户现场查看文档，照着命令敲，其实是很LOW的一件事，问题是很多时候，现场不允许带着你的笔记本和手机，你怎么办。很多常用的命令需要我们记住，随手捏来，每天花费半个小时边敲边理解是很好学习方式。

下面的诊断命令你能在理解的基础上盲敲下来么？？？

[root@11g-ocp ~]# date
Mon Dec 24 06:40:05 CST 2018
[root@11g-ocp ~]# su - oracle
<11g-ocp:orcl:/home/oracle>$sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Mon Dec 24 06:40:12 2018

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, Automatic Storage Management, OLAP and Real Application Testing options

SQL> select sysdate from dual;

SYSDATE
-----------------------
24-DEC-2018 06:40:18

SQL> oradebug setmypid;
Statement processed.
SQL> oradebug event 10046 trace name context forever,level 12;
Statement processed.
SQL> select count(*) from t;

  COUNT(*)
----------
         1

SQL> oradebug event 10046 trace name context off;
Statement processed.
SQL> oradebug tracefile_name;
/u01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_ora_2761.trc
SQL> !tkprof /u01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_ora_2761.trc ./1224.trc

TKPROF: Release 11.2.0.4.0 - Development on Mon Dec 24 06:41:30 2018

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

SQL> !more ./1224.trc

TKPROF: Release 11.2.0.4.0 - Development on Mon Dec 24 06:41:30 2018

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

Trace file: /u01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_ora_2761.trc
Sort options: default

********************************************************************************
count    = number of times OCI procedure was executed
cpu      = cpu time in seconds executing 
elapsed  = elapsed time in seconds executing
disk     = number of physical reads of buffers from disk
query    = number of buffers gotten for consistent read
current  = number of buffers gotten in current mode (usually for update)
rows     = number of rows processed by the fetch or execute call
********************************************************************************

SQL ID: cyzznbykb509s Plan Hash: 2966233522

select count(*) 
from
 t

call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch        2      0.00       0.00          0          2          0           1
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total        4      0.00       0.00          0          2          0           1

Misses in library cache during parse: 0
Optimizer mode: ALL_ROWS
Parsing user id: SYS
Number of plan statistics captured: 1

Rows (1st) Rows (avg) Rows (max)  Row Source Operation
---------- ---------- ----------  ---------------------------------------------------
         1          1          1  SORT AGGREGATE (cr=2 pr=0 pw=0 time=65 us)
         1          1          1   TABLE ACCESS FULL T (cr=2 pr=0 pw=0 time=37 us cost=2 size=0 card=1)

Elapsed times include waiting on following events:
  Event waited on                             Times   Max. Wait  Total Waited
  ----------------------------------------   Waited  ----------  ------------
  SQL*Net message to client                       2        0.00          0.00
  SQL*Net message from client                     2       10.31         10.31

********************************************************************************

OVERALL TOTALS FOR ALL NON-RECURSIVE STATEMENTS

call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch        2      0.00       0.00          0          2          0           1
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total        4      0.00       0.00          0          2          0           1

Misses in library cache during parse: 0

Elapsed times include waiting on following events:
  Event waited on                             Times   Max. Wait  Total Waited
  ----------------------------------------   Waited  ----------  ------------
  SQL*Net message to client                       3        0.00          0.00
  SQL*Net message from client                     3       10.31         15.89

OVERALL TOTALS FOR ALL RECURSIVE STATEMENTS

call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        0      0.00       0.00          0          0          0           0
Execute      0      0.00       0.00          0          0          0           0
Fetch        0      0.00       0.00          0          0          0           0
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total        0      0.00       0.00          0          0          0           0

Misses in library cache during parse: 0

    1  user  SQL statements in session.
    0  internal SQL statements in session.
    1  SQL statements in session.
********************************************************************************
Trace file: /u01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_ora_2761.trc
Trace file compatibility: 11.1.0.7
Sort options: default

       1  session in tracefile.
       1  user  SQL statements in trace file.
       0  internal SQL statements in trace file.
       1  SQL statements in trace file.
       1  unique SQL statements in trace file.
      62  lines in trace file.
       0  elapsed seconds in trace file.

SQL>