SELECT C.PAYDATE
FROM REP_XUQI_PAYDETAIL B,REP_XUQI_NEW C
WHERE B.CONTNO = C.CONTNO
AND C.RISKCODE = B.RISKCODE
AND B.PAYCOUNT = C.PAYCOUNT

上边sql只走B表索引，不走C表索引是怎么回事:
Id Operation Name Rows Bytes Cost Time
0 SELECT STATEMENT 12062357 808177919 2281090 07:36:14

• 1 . HASH JOIN 12062357 808177919 2281090 07:36:14
  2 … INDEX FAST FULL SCAN IDX_PAYDETAIL_3 12062357 349808353 18383 00:03:41
  3 … TABLE ACCESS FULL REP_XUQI_NEW 84970823 3228891274 2037113 06:47:26