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ActiveRecord type of integer (tinyint, smallint, mediumint, int, bigint)
# activerecord-3.0.0/lib/active_record/connection_adapters/mysql_adapter.rb
# Maps logical Rails types to MySQL-specific data types.
def type_to_sql(type, limit = nil, precision = nil, scale = nil)
return super unless type.to_s == 'integer'
case limit
when 1; 'tinyint'
when 2; 'smallint'
when 3; 'mediumint'
when nil, 4, 11; 'int(11)' # compatibility with MySQL default
when 5..8; 'bigint'
else raise(ActiveRecordError, "No integer type has byte size #{limit}")
# ActiveRecord Migrate
create_table 'example' do |t|
t.integer :int # int (4 bytes, max 2,147,483,647)
t.integer :int1, :limit => 1 # tinyint (1 byte, -128 to 127)
t.integer :int2, :limit => 2 # smallint (2 bytes, max 32,767)
t.integer :int3, :limit => 3 # mediumint (3 bytes, max 8,388,607)
t.integer :int4, :limit => 4 # int (4 bytes)
t.integer :int5, :limit => 5 # bigint (8 bytes, max 9,223,372,036,854,775,807)
t.integer :int8, :limit => 8 # bigint (8 bytes)
t.integer :int11, :limit => 11 # int (4 bytes)
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mathieujobin commented Dec 22, 2016

in case you land here looking for a 16 bytes integer.
you have to use binary(16)
I am testing the idea of adding a real uuid column to AR Mysql adapter

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uhrohraggy commented Aug 23, 2019

Still in love with this all these years later, thanks!

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zavan commented May 19, 2022

This is how it's defined in Rails v5, v6 and v7:

def integer_to_sql(limit)
  case limit
  when 1; "tinyint"
  when 2; "smallint"
  when 3; "mediumint"
  when nil, 4; "int"
  when 5..8; "bigint"
  else raise ArgumentError, "No integer type has byte size #{limit}. Use a decimal with scale 0 instead."

Note the omission of 11, which was present until Rails v4.

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