Solution for MySQL The table is full

The size of the memory table exceeds the specified range

MySQL has the problem of "the table is full", generally for two reasons:

One, need to increase the size of the data table

vi /etc/my.cnf

You need to modify the MySQL configuration file my.cnf, add/modify two lines under [mysqld]:

tmp_table_size = 1024Mmax_heap_table_size = 1024M

The system default is 16M, restart mySQL after modification

Second, the hard disk space of the server is full, just clean up the garbage/useless data

#Query server space usagedf -h

Query MySQL storage directory storage usage

#Query the size of all files in a specific directorydu -sh /usr/data/*

tmp_table_size

Memory cache size of temporary table
(Temporary table refers to the temporary data table generated when sql is executed)

# tmp_table_sizeDefault value 16777216Minimum 1Maximum 18446744073709551615// The unit byte default value is more than 16M

View tmp_table_size
show global variables like 'tmp_table_size';

Set tmp_table_size
set global tmp_table_size= 1073741824; (effective immediately after restart)

Add tmp_table_size under mysqld in the MySQL configuration file my.cnf
[mysqld]
tmp_table_size = 100000000

First of all, when optimizing SQL, you should try to avoid temporary tables
If you must use temporary tables and execute a large number of SQL at the same time to generate a large number of temporary tables, increase tmp_table_size appropriately
If the amount of data generated in the temporary table is greater than tmp_table_size, thenStore temporary tables on disk instead of memory

Note
[max_heap_table_size in MySQL

](https://link.jianshu.com/t=https://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_max_heap_table_size) parameter also affectsThe memory cache size of the temporary table max_heap_table_size is the table size of the MEMORY memory engine because the temporary table is also a memory table, so it is also limited by this parameter, so if you want to increase the The size of tmp_table_size also needs to increase the size of max_heap_table_size

You can analyze whether you need to increase tmp_table_size

through the status of Created_tmp_disk_tables and Created_tmp_tables

View Statusshow global status like 'Created_tmp_disk_tables';show global status like 'Created_tmp_tables';Created_tmp_disk_tables : number of disk temporary tablesCreated_tmp_tables : the number of in-memory temporary tables

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MySQL5.7 Reference Manual - tmp_table_size

Related articles on MySQL memory allocation
http://mysql.rjweb.org/doc.php/memory

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