创建索引前后执行计划的变更和软硬解析的比较(三)
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| 0 | SELECT STATEMENT | | 1 | 79 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS BY INDEX ROWID| TT | 1 | 79 | 2 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | TT_IDX | 1 | | 1 (0)| 00:00:01 |
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Predicate Information (identified by operation id):
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2 - access("OBJECT_ID"=10)
Note
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- dynamic sampling used for this statement
Statistics
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9 recursive calls
0 db block gets
79 consistent gets
1 physical reads
0 redo size
481 bytes sent via SQL*Net to client
400 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL>
实验证明，虽然该条语句跟在之前执行过，并且SQL共享区有该语句的副本，但是依然执行了硬解析，且优化器走了索引；
在10g及以上版本中，如果表没有经过分析，oracle 自动通过动态采样的方式来收集分析数据。