Advanced learning of MySQL -- Application -- Optimization of other SQL statements

Optimization when inserting data

Batch insert

Once inserted 500 To 1000 It is more appropriate , It is not recommended to insert more than 1000 pieces at a time .
If you want to insert tens of thousands of pieces ?
It can be , Split into multiple SQL sentence :

It is recommended to commit transactions manually

When multiple insert statements , It is recommended to start the transaction first , Commit multiple insert statements as one transaction .

It is recommended to insert the primary key in sequence

The primary key is out of order , The performance is much better .

Mass insert data

For example, , There is a business to insert millions , Tens of millions of data records .
At this time to use insert The performance of is too low , You can use MySQL Database provides load Insert instructions , The operation is as follows :

On the left is the original disk file structure , On the right is load Watch after coming in
explain , Files that conform to certain rules , Not necessarily a comma , Colon when possible , wait
demonstration :
When the client connects to the server , Add parameters --local-infile -u root -p
mysql --local-infile -u root -p
Set global parameters local_infile by 1, Turn on the switch to import data from the local load file
set global local_infile = 1;
perform load The instruction will prepare the data , Load into table structure
load data local infile '/root/sql1.log' into table 'tb_user' fields terminated by ',' lines terminated by '\n';

Primary key optimization

How data is organized

stay InnoDb In the storage engine , Table data is organized and stored according to the primary key sequence , The tables in this way of storage are called index organization tables .

For clustered indexes , What is stored below is , Table row data .

If the primary key is inserted out of order , Page splitting may occur

If there is page splitting, there is page merging

Key design principles

order by Optimize

group by Optimize

limit Optimize

count Optimize

update Optimize