从以上可以看出虚拟索引也是不准的，ｏｒａｃｌｅ有可能使用虚拟索引也有可能不使用虚拟索引。
不可见索引和虚拟索引。(三)
: 3956160932
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| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
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| 0 | SELECT STATEMENT | | 1 | 32 | 6 (0)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| EMP | 1 | 32 | 6 (0)| 00:00:01 |
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Predicate Information (identified by operation id):
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1 - filter("EMPNO"=7369)
SQL> alter session set "_use_nosegment_indexes"=false;
SQL> drop index EMP_NOSEGMENT_IDX1
2 ;
SQL> create index EMP_NOSEGMENT_IDX1 on emp(empno);
SQL> select * from emp where empno=7369;
Execution Plan
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Plan hash value: 612339345
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| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 32 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS BY INDEX ROWID| EMP | 1 | 32 | 2 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | EMP_NOSEGMENT_IDX1 | 1 | | 1 (0)| 00:00:01 |
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Predicate Information (identified by operation id):
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2 - access("EMPNO"=7369)
SQL>