# Index Join 

+ `Index Join` 
  + `EXPLAIN SELECT /*+ INL_JOIN(t1, t2) */ * FROM t1 INNER JOIN t2 ON t1.id = t2.t1_id;` 
```7
+---------------------------------+-----------+-----------+------------------------------+--------------------------------------------------------------------------------+
| id                              | estRows   | task      | access object                | operator info                                                                  |
+---------------------------------+-----------+-----------+------------------------------+--------------------------------------------------------------------------------+
| IndexJoin_10                    | 180000.00 | root      |                              | inner join, inner:IndexLookUp_9, outer key:test.t1.id, inner key:test.t2.t1_id |
| ├─TableReader_28(Build)         | 142020.00 | root      |                              | data:TableFullScan_27                                                          |
| │ └─TableFullScan_27            | 142020.00 | cop[tikv] | table:t1                     | keep order:false                                                               |
| └─IndexLookUp_9(Probe)          | 1.27      | root      |                              |                                                                                |
|   ├─IndexRangeScan_7(Build)     | 1.27      | cop[tikv] | table:t2, index:t1_id(t1_id) | range: decided by [eq(test.t2.t1_id, test.t1.id)], keep order:false            |
|   └─TableRowIDScan_8(Probe)     | 1.27      | cop[tikv] | table:t2                     | keep order:false                                                               |
+---------------------------------+-----------+-----------+------------------------------+--------------------------------------------------------------------------------+
6 rows in set (0.00 sec)
```
------------------------------------------------------------

Index Join, also known as Index Nested Loop Join, is a join method that does not scan a table and only performs a nested loop on the index. For scenario where the appearance is filtered by a WHERE condition and the result set is small (less than 10K rows), consider using Index Join.