Once and for all: Rails migrations integer :limit option

• tagged MySQL, Rails, Ruby on Rails, integer, limit, migrations and sql • 99 words • ~1 minutes

I literally always have to look up the meaning of :limit in migrations when it comes to integer values. Here’s an overview. Now let’s memorise it (oh, this works for MySQL, other databases may work differently):

:limit Numeric Type Column Size Max value
1 tinyint 1 byte 127
2 smallint 2 bytes 32767
3 mediumint 3 byte 8388607
nil, 4, 11 int(11) 4 byte 2147483647
5..8 bigint 8 byte 9223372036854775807

Note: by default MySQL uses signed integers and Rails has no way (that I know of) to change this behaviour. Subsequently, the max. values noted are for signed integers.


Hey! I'm a software engineer building rock solid back-end systems using Ruby, Ruby on Rails and Golang. In my free time I like to play the piano and experiment with electronics.

I'd love to hear your questions and comments on this article: just mention me on twitter or dispatch an email. Cheers!