Plan hash value: 1950795681
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| Id | Operation | Name | Rows | Cost (%CPU)| Time |
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| 0 | SELECT STATEMENT | | 1 | 5009 (1)| 00:00:26 |
| 1 | SORT AGGREGATE | | 1 | | |
| 2 | TABLE ACCESS FULL| TEST | 10000 | 5009 (1)| 00:00:26 |
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可以看到更改db_file_multiblock_read_count对于成本没有任何影响，因为工作量模式下的COST只跟MBRC有关。