What is the principle of Mysql lock mechanism?

This article mainly introduces "what is the principle of Mysql lock mechanism". In daily operation, I believe many people have doubts about what is the principle of Mysql lock mechanism. Xiaobian consulted all kinds of information and sorted out simple and easy operation methods. I hope to help you answer the doubts of "what is the principle of Mysql lock mechanism"! Next, please follow the small series to learn together!

I. Locking mechanisms of different storage engines

Mysql has multiple storage engines, and the locking mechanisms of different storage engines are different;

2. Locking mechanism of InnoDB

InnoDB contains two types of locks: row locks and table locks.

1. When updating data, if there is an index in the where condition, it is a row lock, otherwise it is a table lock;

2. InnoDB row locks have both pessimistic locks and optimistic locks.

Optimistic lock: By default, update sql we write is optimistic lock, that is, only when the update operation is submitted, it will detect whether the version of the row has changed, and update if there is no change (MVCC mechanism).

Pessimal lock: such as select * from table where id = '1001' for update, this is a pessimistic lock, other transactions can not be updated.

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