你能帮我完成这个我不明白的计划吗？我正在运行一个非常简单的请求：
SELECT *
FROM BOOKING.BOOKING_GRID BG
WHERE BG.hotel=128 and day between 8600 and 8602;
和另一个版本：
SELECT *
FROM BOOKING.BOOKING_GRID BG
WHERE BG.hotel=128 and day in (8600,8601,8602);
我不明白为什么“中间”版本使用 BOOKING_GRID_INDEX5 而“in”版本不使用？表现很不一样！是不是因为IOT索引不能进行“范围扫描”？
谢谢您的帮助！
表索引为：
BOOKING BOOKING_GRIDPK UNIQUE VALID IOT - TOP N NO NO HOTEL, DAY, BOOKINGSTATE
BOOKING BOOKING_GRID_UNIQ UNIQUE VALID NORMAL N NO NO HOTEL, DAY, BOOKING, VALIDITYSTART
BOOKING BOOKING_GRID_INDEX5 NONUNIQUE VALID NORMAL N NO NO HOTEL, BOOKINGSTATUS, ISDAYUSE, DAY
BOOKING BOOKING_GRID_INDEX7 NONUNIQUE VALID NORMAL N NO NO HOTEL, BOOKING, VALIDITYSTART
BOOKING BOOKING_GRID_INDEX10 NONUNIQUE VALID NORMAL N NO NO HOTEL, ISDAYUSE, BOOKINGSTATUS, DAY
这就是我得到的：
SQL> SELECT *
2 FROM BOOKING.BOOKING_GRID BG
3 WHERE BG.hotel=128 and day between 8600 and 8602;
3584 ligne(s) sÚlectionnÚe(s).
Plan d'exÚcution
----------------------------------------------------------
Plan hash value: 1060169596
-----------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-----------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 6504 | 508K| 845 (5)| 00:00:11 |
|* 1 | INDEX UNIQUE SCAN| BOOKING_GRIDPK | 6504 | 508K| 845 (5)| 00:00:11 |
|* 2 | INDEX SKIP SCAN | BOOKING_GRID_INDEX5 | 464 | | 480 (7)| 00:00:06 |
-----------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - access("BG"."HOTEL"=128 AND "DAY">=8600 AND "DAY"<=8602)
2 - access("BG"."HOTEL"=128 AND "DAY">=8600 AND "DAY"<=8602)
filter("DAY">=8600 AND "DAY"<=8602)
Statistiques
----------------------------------------------------------
58 recursive calls
0 db block gets
6961 consistent gets
0 physical reads
0 redo size
200030 bytes sent via SQL*Net to client
3142 bytes received via SQL*Net from client
240 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
3584 rows processed
SQL> SELECT *
2 FROM BOOKING.BOOKING_GRID BG
3 WHERE BG.hotel=128 and day in(8600,8601,8602);
3584 ligne(s) sÚlectionnÚe(s).
Plan d'exÚcution
----------------------------------------------------------
Plan hash value: 1233826949
------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1869 | 146K| 681 (0)| 00:00:09 |
| 1 | INLIST ITERATOR | | | | | |
|* 2 | INDEX RANGE SCAN| BOOKING_GRIDPK | 1869 | 146K| 36 (0)| 00:00:01 |
------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("BG"."HOTEL"=128 AND ("DAY"=8600 OR "DAY"=8601 OR "DAY"=8602))
Statistiques
----------------------------------------------------------
57 recursive calls
0 db block gets
687 consistent gets
0 physical reads
0 redo size
200192 bytes sent via SQL*Net to client
3142 bytes received via SQL*Net from client
240 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
3584 rows processed
添加时间：2013 年 9 月 9 日
每个索引的聚类因子详细信息：
Table Index Cluster. factor Table NRows
BOOKING_GRID BOOKING_GRID_INDEX7 276 816 902 313 290 258
BOOKING_GRID BOOKING_GRID_UNIQ 131 055 933 313 290 258
BOOKING_GRID BOOKING_GRID_INDEX10 121 702 397 313 290 258
BOOKING_GRID BOOKING_GRIDPK 108 115 708 313 290 258
BOOKING_GRID BOOKING_GRID_INDEX5 24 238 404 313 290 258