INSERT IGNORE: id grows unevenly. How to avoid it?

Question

PHP

AUTO_INCREMENT does not grow evenly.
INSERT IGNORE INTO tbl (smth) VALUES (...), (...), (...), ...

Answer 1

On insert ignore, auto-increment id increments by default in innodb tables.
This can be fixed using the innodb_autoinc_lock_mode parameter, but with performance degradation.
In general, this is not a problem if your code requires the id to be non-breaking - you are most likely doing something wrong.

Answer 2

Well, goblin with him, let him grow. Trying to do sequential numbering with gap control will create a bottleneck.