mysql autoincrement在innodb中不是顺序的

Question

Mysql autoincrmenting is not sequential.

when i was trying to upload csv bulk data it's skipping some of the auto increment id

The auto increment id is not sequential

The db engine is innodb & id is auto increment

example

id      color 
    1      red
    2      blue
    3      green
    4      orange
    9      pink
    10     white
    11     black 
    16     gray
    17     brown

The id is not sequential.

Answer 1

don't know about codeignitor and specifics of transactions, but i do know that "catched fails" in queries (like insert ignore ) have the effect of NOT inserting, but DO increment the auto_increment. Look for your answer here. And for the rest don't bother 'fixing' this.

Answer 2

If you are using MySQL newer than 5.1.22 this can be caused because of the InnoDB locking strategy as Miguel Angel Nieto explains in this blog post .

You can change this behavior setting the innodb_autoinc_lock_mode parameter:

• innodb_autoinc_lock_mode = 0 : “traditional” lock mode , same behavior as before 5.1.22
• innodb_autoinc_lock_mode = 1 : “consecutive” lock mode , default behavior, this is probably what you have set, it's designed to improve concurrency and performance with the drawback of having holes on the sequence.
• innodb_autoinc_lock_mode = 2 : “interleaved” lock mode , this is the fastest and most scalable lock mode, but it is not safe when using statement-based replication or recovery scenarios when SQL statements are replayed from the binary log

For a detailed information o the use of innodb_autoinc_lock_mode you can check the detailed mysql documentation .