看了索引的数据段分布，现在可以理解本地索引的一致性读与物理读为什么那么高，这是因为查找 objkey='810000836'这个值要去每个分区的段中查找，并将结果合并后返回。
创建分区字段的索引比较
SQL> CREATE INDEX PI_T65_F_S_PGZ10023_M_DT ON T65_F_S_PGZ10023_M (STATISTIC_DT) TABLESPACE TSDAT01 LOCAL;
SQL> exec dbms_stats.gather_table_stats(ownname => 'AML',tabname => 'T65_F_S_PGZ10023_M');
SQL> select * from T65_F_S_PGZ10023_M where STATISTIC_DT=to_date('2012-01-04','yyyy-mm-dd');
99999 rows selected.
Execution Plan
----------------------------------------------------------
Plan hash value: 3412225213
-------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
-------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 99990 | 3027K| 141 (3)| 00:00:02 | | |
| 1 | PARTITION RANGE SINGLE | | 99990 | 3027K| 141 (3)| 00:00:02 | 5 | 5 |
|* 2 | TABLE ACCESS FULL | T65_F_S_PGZ10023_M | 99990 | 3027K| 141 (3)| 00:00:02 | 5 | 5 |
-------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter("STATISTIC_DT"=TO_DATE(' 2012-01-04 00:00:00', 'syyyy-mm-dd hh24:mi:ss'))
Note
-----
- dynamic sampling used for this statement
Statistics
----------------------------------------------------------
1 recursive calls
0 db block gets
7188 consistent gets
549 physical reads
0 redo size
3186021 bytes sent via SQL*Net to client
73818 bytes received via SQL*Net from client
6668 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
99999 rows processed
创建全局索引的执行计划
SQL> drop index PI_T65_F_S_PGZ10023_M_DT;
SQL> CREATE INDEX I_T65_F_S_PGZ10023_M_DT ON T65_F_S_PGZ10023_M (STATISTIC_DT) TABLESPACE TSDAT01 global;
SQL> alter system flush buffer_cache;
SQL> select * from T65_F_S_PGZ10023_M where STATISTIC_DT=to_date('2012-01-04','yyyy-mm-dd');
99999 rows selected.
Execution Plan
----------------------------------------------------------
Plan hash value: 3412225213
-------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
-------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 99991 | 3027K| 141 (3)| 00:00:02 | | |
| 1 | PARTITION RANGE SINGLE| | 99991 | 3027K| 141 (3)| 00:00:02 | 5 | 5 |
|* 2 | TABLE ACCESS FULL | T65_F_S_PGZ10023_M | 99991 | 3027K| 141 (3)| 00:00:02 | 5 | 5 |
-------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter("STATISTIC_DT"=TO_DATE(' 2012-01-04 00:00:00', 'syyyy-mm-dd hh24:mi:ss'))
Statistics
----------------------------------------------------------
1 recursive calls
0 db block gets
7188 consistent gets
549 physical reads
0 redo size
3186021 bytes sent via SQL*Net to client
73818 bytes received via SQL*Net from client
6668 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
99999 rows processed
STATISTIC_DT字段索引比较
Statistics
本地索引（LOCAL）
全局索引（GLOBAL）
recursive calls （递归调用）
1
1
db block gets （数据块）
0
0
consistent get (一致性读)
7188
7188
physical reads （物理读）
549
549
redo size
0
0
bytes sent via SQL*Net to client
3186014
3186014
bytes received via SQL*Net from client
73818
73818
SQL*Net roundtrips to/from client
6668
6668
sorts (memory)
0
0
sorts (disk)
0
0
rows processed
99999
99999