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This article mainly explains "how to understand mysql innodb's line lock". The explanation content in this article is simple and clear, easy to learn and understand. Please follow Xiaobian's thinking slowly and deeply to study and learn "how to understand mysql innodb's line lock" together!

Lock based on index, not on selected rows

root@sakila 10:14:32>show index from tab_no_index \G

*************************** 1. row ***************************

Table: tab_no_index

Non_unique: 1

Key_name: id

Seq_in_index: 1

Column_name: id

Collation: A

Cardinality: 5

Sub_part: NULL

Packed: NULL

Null: YES

Index_type: BTREE

Comment:

Index_comment:

1 row in set (0.00 sec)

the first session

root@sakila 10:18:39>select * from tab_no_index where id=1 and name='1' for update;

+------+------+

| id | name |

+------+------+

| 1 | 1 |

+------+------+

1 row in set (0.00 sec)

the second session

root@sakila 10:18:42>select * from tab_no_index where id=1 and name='4' for update;

ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction

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