cmd的sql执行计划各项属性说明

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Operation -是当前操作的内容
Name --操作的数据库对象
Rows --当前操作的基数，也就是count(*)
Bytes --所占用的物理空间
Cost (%CPU) --计算出来的数值，用于说明SQL执行的代价
Time --估算当前操作的时间

执行计划

----------------------------------------------------------
Plan hash value: 1301846388

----------------------------------------------------------------------------------------
| Id | Operation                    | Name    | Rows | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |         |    14 |   364 |     4   (0)| 00:00:01 |
|   1 | NESTED LOOPS OUTER          |         |    14 |   364 |     4   (0)| 00:00:01 |
|   2 |   TABLE ACCESS FULL          | EMP     |    14 |   182 |     3   (0)| 00:00:01 |
|   3 |   TABLE ACCESS BY INDEX ROWID| DEPT    |     1 |    13 |     1   (0)| 00:00:01 |
|* 4 |    INDEX UNIQUE SCAN         | PK_DEPT |     1 |       |     0   (0)| 00:00:01 |
----------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   4 - access("T1"."DEPTNO"="T2"."DEPTNO"(+))

统计信息
----------------------------------------------------------
          0 recursive calls
          0 db block gets
         24 consistent gets --逻辑读，也可做为SQL性能分析指标，适合大部分的场景
          0 physical reads
          0 redo size
        947 bytes sent via SQL*Net to client
        385 bytes received via SQL*Net from client
          2 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
         14 rows processed

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