Based on what I've found, I'm using this right now, but it's not working...
def change
change_column :users, :twitter_id, :integer, :limit => 8
end
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1Still, if someone has an answer for how to do this with a change, I will mark it as the correct answer. Doing what I did solved the problem, but isn't really an answer to the question as it won't help anyone who comes across this problem later in the game when they can't just drop a table from their databaseCarl– Carl2015-10-22 10:59:46 +00:00Commented Oct 22, 2015 at 10:59
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2 Answers
I just ran into the same issue. The following worked for me:
def up
change_column :my_table, :my_column, :bigint
end
8 Comments
TheJKFever
Does this just change the schema, or will every row in the table be updated? I.e. will it lock my table?
malikilam
Doing this did not lock my table. In all honestly, I didn't check to see whether every row was changed or whether it was just the schema that was changed. It worked seamlessly, so I had no need to dig into further.
TheJKFever
It definitely does lock the table. I'm pretty sure it's changing every row also. I added a couple dozen million records before a test migration, and I was not able to insert into the table during the migration which took hours. For anyone looking for zero downtime, I found this answer: stackoverflow.com/questions/33504982/…
Foram
Can you please help me same for the small integer?
David Hempy
I'd say this depends on your database. Postgress copies every row, and locks the table. In one scenario, I saw PG process about 1GB of table size/minute...but YMMV.
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For anybody looking for different data types than :bigint, you can use :tinyint, :smallint and :mediumint as well, according to 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}")
end
end
Also, do use up and down for rails db:rollback; this is what worked for me:
class ChangeCarNumberOfKeysToSmallInt < ActiveRecord::Migration[5.2]
def up
change_column :cars, :number_of_keys, :tinyint
end
def down
change_column :cars, :number_of_keys, :int
end
end
