Oracle 查看执行计划的几种方式

• set autotrace on

• explain plan
  explain plan for select 0 from dual;
  select * from table(dbms_xplan.display)

• 10046事件
  alter session setevents ‘10046 trace name context forever,level 12’; （开启跟踪）
  执行sql
  alter session setevents ‘10046 trace name context off’; （关闭跟踪）
  步骤4：找到跟踪后产生的文件
  tkprof trc文件 目标文件 sys=no sort=prsela,exeela,fchela （格式化命令）
  例子：

  SQL> set autot off
  SQL> alter session set statistics_level=typical;
   
  Session altered.
   
  SQL> alter session set events '10046 trace name context forever,level 12';
   
  Session altered.
   
  SQL> select count(*) from test;
   
    COUNT(*)
  ----------
           7
   
  SQL> alter session set events '10046 trace name context off';
   
  Session altered.
   
  SQL> select d.value
    2  || '/'
    3  || LOWER (RTRIM(i.INSTANCE, CHR(0)))
    4  || '_ora_'
    5  || p.spid
    6  || '.trc' trace_file_name
    7  from (select p.spid
    8        from v$mystat m,v$session s, v$process p
    9        where  m.statistic#=1 and s.sid=m.sid and p.addr=s.paddr) p,
   10        (select t.INSTANCE
   11         FROM v$thread t,v$parameter v
   12         WHERE v.name='thread'
   13         AND(v.VALUE=0 OR t.thread#=to_number(v.value))) i,
   14         (select value
   15         from v$parameter
   16         where name='user_dump_dest') d;
   
  TRACE_FILE_NAME
  --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  /u01/app/oracle/diag/rdbms/ora12c/ora12c/trace/ora12c_ora_12195.trc
   
  SQL> host
  [oracle@ora12c ~]$ tkprof /u01/app/oracle/diag/rdbms/ora12c/ora12c/trace/ora12c_ora_12195.trc /home/oracle/10046.txt sys=no sort=prsela,exeela,fchela
   
  TKPROF: Release 12.1.0.1.0 - Development on Fri Jan 20 08:22:25 2017
   
  Copyright (c) 1982, 2013, Oracle and/or its affiliates.  All rights reserved.
   
  SQL ID: 7b2twsn8vgfsc Plan Hash: 784602781
   
  select count(*) 
  from
   test
   
   
  call     count       cpu    elapsed       disk      query    current        rows
  ------- ------  -------- ---------- ---------- ---------- ----------  ----------
  Parse        1      0.00       0.00          3          3          2           0
  Execute      1      0.00       0.00          0          0          0           0
  Fetch        2      0.00       0.00          4         66          0           1
  ------- ------  -------- ---------- ---------- ---------- ----------  ----------
  total        4      0.00       0.00          7         69          2           1
   
  Misses in library cache during parse: 1
  Optimizer mode: ALL_ROWS
  Parsing user id: 103  
  Number of plan statistics captured: 1
   
  Rows (1st) Rows (avg) Rows (max)  Row Source Operation
  ---------- ---------- ----------  ---------------------------------------------------
           1          1          1  SORT AGGREGATE (cr=66 pr=4 pw=0 time=298 us)
           7          7          7   PARTITION RANGE ALL PARTITION: 1 3 (cr=66 pr=4 pw=0 time=397 us cost=39 size=0 card=11)
           7          7          7    TABLE ACCESS FULL TEST PARTITION: 1 3 (cr=66 pr=4 pw=0 time=290 us cost=39 size=0 card=11)
   
   
  Elapsed times include waiting on following events:
    Event waited on                             Times   Max. Wait  Total Waited
    ----------------------------------------   Waited  ----------  ------------
    db file sequential read                         4        0.00          0.00
    SQL*Net message to client                       2        0.00          0.00
    db file scattered read                          1        0.00          0.00
    SQL*Net message from client                     2        7.03          7.03
  

• statistics_level=all
  alter session setstatistics_level=all;
  执行sql
  select * fromtable(dbms_xplan.display_cursor(null,null,‘allstats last’));

• dbms_xplan.display_cursor输入sql_id参数直接获取
  select * fromtable(dbms_xplan.display_cursor(’&sq_id’)); #从共享池获取

• awrsqlrpt.sql
  @?/rdbms/admin/awrsqrpt.sql
  选择你要的断点（begin snap 和end snap)
  输入sql_id