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  • INDEX RANG SCAN无需回表的情况

    create table a3 as select * from dba_objects
    
    create index a3_idx1 on a3(owner);
    
    
    select owner from a3 where owner='SCOTT';
    
    
    SQL> set linesize 200
    SQL> set pagesize 200
    SQL> set autot trace
    SQL> select owner from a3 where owner='SCOTT';
    
    1870 rows selected.
    
    
    Execution Plan
    ----------------------------------------------------------
    Plan hash value: 3836947260
    
    ----------------------------------------------------------------------------
    | Id  | Operation	 | Name    | Rows  | Bytes | Cost (%CPU)| Time	   |
    ----------------------------------------------------------------------------
    |   0 | SELECT STATEMENT |	   |  1870 | 31790 |	 5   (0)| 00:00:01 |
    |*  1 |  INDEX RANGE SCAN| A3_IDX1 |  1870 | 31790 |	 5   (0)| 00:00:01 |
    ----------------------------------------------------------------------------
    
    Predicate Information (identified by operation id):
    ---------------------------------------------------
    
       1 - access("OWNER"='SCOTT')
    
    Note
    -----
       - dynamic sampling used for this statement (level=2)
    
    
    Statistics
    ----------------------------------------------------------
    	  7  recursive calls
    	  0  db block gets
    	212  consistent gets
    	  0  physical reads
    	  0  redo size
          25551  bytes sent via SQL*Net to client
           1783  bytes received via SQL*Net from client
    	126  SQL*Net roundtrips to/from client
    	  0  sorts (memory)
    	  0  sorts (disk)
           1870  rows processed
    

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  • 原文地址:https://www.cnblogs.com/hzcya1995/p/13352372.html
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