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# How to change innodb\_read\_io\_threads in MySQL

I will give an example of changing innodb\_read\_io\_threads in MySQL.\
The innodb\_read\_io\_threads value determines the number of I/O threads for read operations in InnoDB. The default is 4, the minimum possible is 1, the maximum is 64.

I will give an example of viewing the current value:

```
show variables like 'innodb_read_io_threads';
```

You cannot change the value without restarting the MySQL server, I will give an example of an error:

```
SET global innodb_read_io_threads=64;
ERROR 1238 (HY000): Variable 'innodb_read_io_threads' is a read only variable
```

Therefore, we will indicate it in the MySQL server configuration file:

```
[mysqld]
innodb_read_io_threads=64
```

And restart the MySQL server:

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