oracle 数据量太大，查询语句优化。帮帮忙！！！

SELECT A.Aac001,
A.Aac002,
B.Aab001,
B.Ajc090,
B.Aac021
  FROM a
 INNER JOIN b
ON A.Aac021 = B.Aac021
 WHERE B.Aae116 = '1'
AND (B.Ajc090 = To_Date('2011-01-01', 'yyyy-mm-dd') OR
To_Date('2011-01-01', 'yyyy-mm-dd') = To_Date('2011-01-01', 'yyyy-mm-dd'))
AND NOT EXISTS (SELECT Aac021
FROM c
WHERE Aae002 = '201109'
AND C.Aac001 = B.Aac001
AND C.Aac021 = B.Aac021);

SELECT A.Aac001,
  A.Aac002,
  B.Aab001,
  B.Ajc090,
  B.Aac021
FROM a
INNER JOIN
  (SELECT B.Aab001,
  B.Ajc090,
  B.Aac021
  FROM B
  WHERE NOT EXISTS (SELECT Aac021 FROM c WHERE Aae002 = '201109' AND C.Aac001 = B.Aac001 AND C.Aac021 = B.Aac021))
  b ON A.Aac021 = B.Aac021
WHERE B.Aae116 = '1'
AND (B.Ajc090 = To_Date('2011-01-01', 'yyyy-mm-dd') )B

SELECT A.Aac001,
  A.Aac002,
  B.Aab001,
  B.Ajc090,
  B.Aac021
FROM a
INNER JOIN
  (SELECT B.Aab001,
  B.Ajc090,
  B.Aac021
  FROM B
  WHERE NOT EXISTS (SELECT Aac021 FROM c WHERE Aae002 = '201109' AND C.Aac001 = B.Aac001 AND C.Aac021 = B.Aac021))
  b ON A.Aac021 = B.Aac021
WHERE B.Aae116 = '1'
AND (B.Ajc090 = To_Date('2011-01-01', 'yyyy-mm-dd') )