# 执行计划中的算子 扫描数据类算子（D）

+ `Index Lookup` 示例
  + `mysql> EXPLAIN SELECT * FROM t2 USE INDEX(idx_t2_a);` 
```
+-------------------------------+----------+-----------+-----------------------------+------------------+
| id                            | estRows  | task      | access object               | operator info    |
+-------------------------------+----------+-----------+-----------------------------+------------------+
| IndexLookUp_6                 | 10000.00 | root      |                             |                  |
| ├─IndexFullScan_4(Build)      | 10000.00 | cop[tikv] | table:t2, index:idx_t2_a(a) | keep order:false |
| └─TableRowIDScan_5(Probe)     | 10000.00 | cop[tikv] | table:t2                    | keep order:false |
+-------------------------------+----------+-----------+-----------------------------+------------------+
3 rows in set (0.01 sec)
```
-------------------------------------------------------------
Index Lookup 示例
```
mysql> EXPLAIN SELECT * FROM t2 USE INDEX(idx_t2_a);
+-------------------------------+----------+-----------+-----------------------------+------------------+
| id                            | estRows  | task      | access object               | operator info    |
+-------------------------------+----------+-----------+-----------------------------+------------------+
| IndexLookUp_6                 | 10000.00 | root      |                             |                  |
| ├─IndexFullScan_4(Build)      | 10000.00 | cop[tikv] | table:t2, index:idx_t2_a(a) | keep order:false |
| └─TableRowIDScan_5(Probe)     | 10000.00 | cop[tikv] | table:t2                    | keep order:false |
+-------------------------------+----------+-----------+-----------------------------+------------------+
3 rows in set (0.01 sec)
```