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行锁注意事项补充; #1766

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Snailclimb merged 1 commit into from
Jul 3, 2022
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行锁注意事项补充; #1766

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2 changes: 1 addition & 1 deletion docs/database/mysql/mysql-questions-01.md
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Expand Up @@ -334,7 +334,7 @@ InnoDB 不光支持表级锁(table-level locking)，还支持行级锁(row-level

### 行级锁的使用有什么注意事项？

InnoDB 的行锁是针对索引字段加的锁，表级锁是针对非索引字段加的锁。当我们执行 `UPDATE`、`DELETE` 语句时，如果 `WHERE`条件中字段没有命中索引或者索引失效的话，就会导致扫描全表对表中的所有记录进行加锁。这个在我们日常工作开发中经常会遇到，一定要多多注意！！！
InnoDB 的行锁是针对索引字段加的锁，表级锁是针对非索引字段加的锁。当我们执行 `UPDATE`、`DELETE` 语句时，如果 `WHERE`条件中字段没有命中唯一索引或者索引失效的话，就会导致扫描全表对表中的所有记录进行加锁。这个在我们日常工作开发中经常会遇到，一定要多多注意！！！

不过，很多时候即使用了索引也有可能会走全表扫描，这是因为 MySQL 优化器的原因。

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