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MySQL database logic architecture principle is what, many novices are not very clear about this, in order to help you solve this problem, the following small series will be explained in detail for everyone, there are people who need to learn, I hope you can gain something.

A. General logical framework

First give a logical architecture diagram, this diagram is to let you analyze and understand from a macro perspective.

From this picture you can get the following information:

(1) The mysql architecture can be roughly divided into four layers.

(2)The first layer is mainly the connection of different clients.

(3)The second layer deals primarily with client connections.

(4)The third layer deals with SQL statements on the client side.

(5)The fourth layer, the storage engine actually executes sql statements.

Now that you understand the overall structure of mysql and roughly understand what each layer is for, let's gradually refine our vision. After all, the above picture is still too general.

II. Detailed logical architecture diagram

Look at the picture below.

Compared with the previous picture, this picture has been refined a part, and it is divided into four layers from top to bottom.

Layer 1: Here we can see that there are many connected clients, PHP, python, jdbc, etc.

Layer 2: This layer is the link layer, corresponding to the connection processing layer of the first diagram, mainly dealing with client connections, because there are many types of clients.

Level 3: This is the service level. SQL statements that mainly deal with client requests, how to deal with them? The general process is to query the cache first. If there is one in the cache, it will be taken out and returned directly. If not, then the parser parses, and then the optimizer optimizes, and the functions provided by each storage engine are concentrated at this layer, such as stored procedures, triggers, views, etc.

Layer 4: This layer is the engine layer, where we can see that there are several different storage engines, such as InnoDB,MyISAM,memory, etc. It is really responsible for storing and extracting data in MySQL.

Suppose we use jdbc to execute an inserted sql statement, how does the process work?

First of all, jdbc belongs to the first layer and connects to mysql server through the connection processing of the second layer. Next, SQL statement is parsed by parser, and then SQL statement is optimized by optimizer. Finally, the interface of storage engine of the fourth layer is called to execute insert statement and insert data into file or other file system.

It's not that simple. Usually when learning mysql, the teacher will introduce to the storage engine. At that time, you may not have noticed his importance, but now I believe you should realize it. That is, those functions of the service layer are provided by the storage engine. Different storage engines may provide different results. How do you compare these storage engines? Here are some indicators to compare:

For mysql databases, the default is InnoDB, which does not support hash indexes or full-text indexes. So if one day you don't like it, you can change it, and the statement is SET default_storage_engine=

。

Did reading the above help you? If you still want to have further understanding of related knowledge or read more related articles, please pay attention to the industry information channel, thank you for your support.

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