--explain查看SQL执行计划
EXPLAIN  PLAN FOR select count(*) from steven.AWEN_OGG_TEST;
select * from table(dbms_xplan.display());

--查看AWR和CURSOR中的执行计划
select * from table(dbms_xplan.display_awr('&sqlid'));
select * from table(dbms_xplan.display_cursor('&sqlid'));

--查看内存中的执行计划
select '| Operation                         |Object Name                    |  Rows | Bytes|   Cost |'
as "Explain Plan in library cache:" from dual
union all
select rpad('| '||substr(lpad(' ',1*(depth-1))||operation||
      decode(options, null,'',' '||options), 1, 35), 36, ' ')||'|'||
      rpad(decode(id, 0, '----------------------------',
      substr(decode(substr(object_name, 1, 7), 'SYS_LE_', null, object_name)
      ||' ',1, 30)), 31, ' ')||'|'|| lpad(decode(cardinality,null,'  ',
      decode(sign(cardinality-1000), -1, cardinality||' ',
      decode(sign(cardinality-1000000), -1, trunc(cardinality/1000)||'K',
      decode(sign(cardinality-1000000000), -1, trunc(cardinality/1000000)||'M',
      trunc(cardinality/1000000000)||'G')))), 7, ' ') || '|' ||
      lpad(decode(bytes,null,' ',
      decode(sign(bytes-1024), -1, bytes||' ',
      decode(sign(bytes-1048576), -1, trunc(bytes/1024)||'K',
      decode(sign(bytes-1073741824), -1, trunc(bytes/1048576)||'M',
      trunc(bytes/1073741824)||'G')))), 6, ' ') || '|' ||
      lpad(decode(cost,null,' ', decode(sign(cost-10000000), -1, cost||' ',
      decode(sign(cost-1000000000), -1, trunc(cost/1000000)||'M',
      trunc(cost/1000000000)||'G'))), 8, ' ') || '|' as "Explain plan"
 from v$sql_plan sp
 where sp.hash_value=&hash_value or sp.sql_id='&sqlid';

--查看历史执行计划
select distinct SQL_ID,PLAN_HASH_VALUE,to_char(TIMESTAMP,'yyyymmdd hh24:mi:ss') TIMESTAMP
 from dba_hist_sql_plan
 where SQL_ID='&sqlid' order by TIMESTAMP;