devroom.io/content/posts/2009-08-20-once-and-for-all-rails-migrations-integer-limit-option.md

+++ date = "2009-08-20" title = "Once and for all: Rails migrations integer :limit option" tags = ["MySQL", "Ruby on Rails", "Rails", "sql", "migrations", "integer", "limit"] slug = "once-and-for-all-rails-migrations-integer-limit-option" +++

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.