Rails BLOB/TEXT column used in key specification without a key length

Question

I am trying to run a rails migration and I am seeing the error "BLOB/TEXT column used in key specification without a key length"... However, I'm specifying the length in the migration class. Rails seems to ignore this when generating the SQL statement from the migration. Any clues?

Here's my migration class:

class AddIndexToAccounts < ActiveRecord::Migration
def self.up
  add_index :TACCOUNT, :NAMEX, :length => 5
end
def self.down
  remove_index :TACCOUNT, :NAMEX
end
end

And here's the error output. It seems to have seen the length specification, but it's not present in the SQL statement that it generates:

** [out :: 192.168.10.7] -- add_index(:TACCOUNT, :NAMEX, {:length=>5})
** [out :: 192.168.10.7] rake aborted!
** [out :: 192.168.10.7] An error has occurred, all later migrations canceled:
** [out :: 192.168.10.7] 
** [out :: 192.168.10.7] Mysql::Error: BLOB/TEXT column 'NAMEX' used in key specification without a key length: CREATE  INDEX `index_TACCOUNT_on_NAMEX` ON `TACCOUNT` (`NAMEX`)

Answer 1

You could try being more specific to see if that tricks it into working:

add_index :TACCOUNT, :NAMEX, :length => { :NAMEX => 5 }

As a last resort you can crete the index the "hard way" using SQL directly by adjusting the incorrect ADD INDEX statement and using execute on the correct one.