常用v_视图

1，找出锁定问题

SELECT /*+ ordered */
 B.USERNAME, B.SERIAL#, D.ID1, A.SQL_TEXT
  FROM V$LOCK D
  JOIN V$SESSION B ON B.LOCKWAIT = D.KADDR
     JOIN V$SQLTEXT A ON A.ADDRESS = B.SQL_ADDRESS
 AND A.HASH_VALUE = B.SQL_HASH_VALUE;

2，检查用户的当前操作及其使用的资源
SELECT A.SID, A.USERNAME, S.SQL_TEXT
  FROM V$SESSION A, V$SQLTEXT S
 WHERE A.SQL_ADDRESS = S.ADDRESS
   AND A.SQL_HASH_VALUE = S.HASH_VALUE
 ORDER BY A.USERNAME, A.SID, S.PIECE;

3，查看v$sql_bind_capture,看看average binds是否大于15
SELECT sql_id,COUNT(*) bind_count FROM v$sql_bind_capture
WHERE child_number=0 GROUP BY sql_id HAVING COUNT(*) >20 ORDER BY COUNT(*) DESC;

4，查看有问题的SQL并修复：
SELECT sql_text,users_executing,executions,users_opening,buffer_gets
FROM v$sqlarea WHERE sql_id='cprfzqn5y3w1h' ORDER BY buffer_gets;

SELECT SIZE_FOR_ESTIMATE,
       BUFFERS_FOR_ESTIMATE,
       ESTD_PHYSICAL_READ_FACTOR,
       ESTD_PHYSICAL_READS
  FROM V$DB_CACHE_ADVICE
 WHERE NAME = 'DEFAULT'
   AND BLOCK_SIZE =
       (SELECT VALUE FROM V$PARAMETER WHERE NAME = 'db_block_size')
   AND ADVICE_STATUS = 'ON';

SELECT sum(gets),SUM(getmisses),(1-SUM(getmisses)/(SUM(gets)+SUM(getmisses))) * 100 HitRate FROM v$rowcache;