MySQL – IT Blog

Zabbix ERROR 1273 (HY000) at line 483: Unknown collation: ‘utf8mb4_0900_ai_ci’

One day I was migrating a Zabbix server database to another server and an error occurred:

Can’t open PID file /run/zabbix/zabbix_server.pid (yet?) after start: No such file or directory

Once, on Ubuntu 18.04.6 LTS, I updated the Zabbix server to version 6.0 LTS and the new version did not start.

Key ‘x’ doesn’t exist in table ‘x’

Once after updating the ABillS billing system, when opening the Maintenance>Hardware>PON menu and selecting a device, an SQL error occurred:

MySQL. Accepted a connection with deprecated protocol ‘TLSv1.1’

One day I noticed warnings in the MySQL logs:

Solution for error 21S01 Column count doesn’t match value count at row 1

Once it was necessary to make a record in the table very quickly and I quickly wrote a SQL query, but after executing it I got an error:

Solution: Specified key was too long; max key length is 767 bytes

Once on Ubuntu Server 18.04 I upgraded Zabbix 4.4 to 5.0 and found an error in the logs during the upgrade:

How to change innodb_flush_method in MySQL

innodb_flush_method defines the method for flushing data from RAM to disk.

Migrating MySQL Directory

Once I created a raid, mounted it as a disk system partition and transferred the MySQL directory directly to it, but in this case there were drawbacks, the lost+found directory could appear, it could not be used for other data, etc., after that I began to transfer the MySQL directory not directly to the partition, but created a directory on it and transferred it to it.

How to change innodb_io_capacity in MySQL

innodb_io_capacity – determines the number of write IOPS for background InnoDB tasks, such as flushing pages from a buffer pool, etc. If the cleanup operation is lagging, then InnoDB can perform cleanup more aggressively at a higher IOPS, which is defined in the innodb_io_capacity_max variable.

Partitioning tables in MySQL

Partitioning tables in MySQL is splitting a large table into parts according to the specified criteria, which will speed up reading and writing data to it if this table contains a very large amount of data.