How to Prevent InnoDB Auto Incrementing on Duplicate Key Updates?

InnoDB Auto Increment Control on Duplicate Keys

MySQL's InnoDB engine provides an auto-incrementing primary key feature for tables, automatically generating unique identifiers for each row. However, by default, InnoDB also increments the primary key on duplicate key updates, leading to non-consecutive values.

Avoiding Auto Increment on Duplicates

To prevent this issue and maintain consecutive auto-increment values, you can modify the innodb_autoinc_lock_mode configuration option. By setting it to "0," you switch to the "traditional" auto-increment locking mode, which ensures that consecutive values are assigned to AUTO_INCREMENT columns even for duplicate key updates.

Configuring InnoDB Auto-Increment Mode

Set the innodb_autoinc_lock_mode value in your MySQL configuration file, typically located at /etc/my.cnf or /my.ini.

[mysqld]
innodb_autoinc_lock_mode=0

Table Structure and Query Example

Your table structure and query in the provided context are as follows:

CREATE TABLE IF NOT EXISTS `table` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `field1` varchar(200) NOT NULL,
  `field2` varchar(255) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `field1` (`field1`),
  KEY `id` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

INSERT INTO table ( field1, field2 ) VALUES (:value1, :value2)
            ON DUPLICATE KEY
            UPDATE field1 = :value1, field2 = :value2 

With innodb_autoinc_lock_mode set to "0," this query will update duplicate records without incrementing the id column, ensuring consecutive values for new insertions.

Caution:

Note that relying on consecutive auto-increment IDs in your application is not a good practice. Auto-increment values are meant to provide unique identifiers and should not be used for ordering or sorting purposes.

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