What is a temporary table in mysql

MySQL temporary tables are very useful when we need to save some temporary data. So what are temporary tables? The following article will introduce it to you, I hope it will be helpful to you.

The temporary table is a table used by MySQL to store some intermediate result sets. The temporary table is only visible in the current connection. When the connection is closed, Mysql will automatically delete the table and release all space. Why is a temporary table generated? Generally, it is due to complex SQL that a large number of temporary tables are created.

Temporary tables were added in MySQL version 3.23. If your MySQL version is lower than version 3.23, you cannot use MySQL's temporary tables. However, nowadays it is generally rare to use such a low version of the MySQL database service.

Temporary tables are divided into two types, one is a memory temporary table and the other is a disk temporary table. The memory temporary table uses the memory storage engine, and the disk temporary table uses the myisam storage engine (disk temporary tables can also use the innodb storage engine. Use the internal_tmp_disk_storage_engine parameter to control which storage engine is used. From mysql5.7.6 onwards, the default is innodb storage. Engine, previous versions defaulted to myisam storage engine). Use the Created_tmp_disk_tables and Created_tmp_tables parameters to view how many disk temporary tables are generated and all generated temporary tables (memory and disk).

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