Where is the self-value-added storage of mysql

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When we use mysql, we will encounter a self-increasing primary key. Then different engines have different self-value-added preservation strategies, and we discuss the location of self-value-added storage in two cases.

1. The self-increment of the MyISAM engine is stored in the data file.

2. The self-increment of the InnoDB engine. In MySQL5.7 and previous versions, the self-increment is stored in memory and will not last.

Every time you restart, when you open the table for the first time, you will find the largest self-added max (id), and then use the max (id) + step as the current self-increment.

Select max (ai_col) from table_name for update

In higher versions of MySQL, self-increment changes are recorded in redolog, and rebooting relies on redolog to restore pre-restart values.

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