The database size remains unchanged after the delete record of mysql is deleted, and mysqldelete

The database size remains unchanged after the delete record of mysql is deleted, and mysqldelete

This problem occurs when conditions are followed after the DELETE operation.

Delete from table_name where Condition

After the data is deleted, the space occupied by the data table does not change.

When the condition is not followed, the delete operation is performed directly.

Delete from table_name

The data is cleared and the data table space is changed to 0.

If a large part of the table data has been deleted, or many changes and variable-length table rows (VARCHAR table, VARBINARY, BLOB, or text column) have been made, this is because fragments are left in the data file after the delete operation. DELETE only deletes data identifiers and does not organize data files. When new data is inserted, the deleted identifiers are used again, you can use optimize table to recycle unused space and sort data file fragments.

Optimize table only applies to MyISAM, BDB, and InnoDB tables.

Optimize table name;

For the myisam engine, optimize table also has the following features:

If the table has deleted or split rows, repair the table. [repair table] If the index pages are not sorted, sort them. [the index is not sorted and will be sorted] If the table's statistics are not up to date (and the repair cocould not be accomplished by sorting the index), update them. [update a table if its statistical information is not up-to-date]

After the myiam data table is deleted in batches, it is found that the space is not recycled. Use optimize table to recycle the space.

The above is a small Editor to introduce you to the mysql delete records after the database size remains unchanged, I hope to help you!