I've been stuck on this from the past 2-3 days. I deleted the folder,
did everything right from the start, but it's still showing the error.
I've been following this
(=>Ruby on Rails 2.1 - Migrations)
tutorial to at least get one rails app working but to no avail.
This is the error I get when I enter the command rake db:migrate:
rake aborted!
Mysql::Error: #42000Specified key was too long; max key length is 767
bytes: CREATE UNIQUE INDEX 'unique_schema_migrations' ON
'schema_migrations' <'version'>
rake aborted!
Mysql::Error: #42000Specified key was too long; max key length is 767
bytes: CREATE UNIQUE INDEX 'unique_schema_migrations' ON
'schema_migrations' <'version'>
hmm
what version of MySQL do you have?
works fine on mine,
should just be running SQL equivalent to;
The problem is that MySQL has a limit of 767 bytes on the length of
columns used for keys. In UTF8 a varchar(255) consumes 1080 bytes. The
fix is to have the indexing done on a the first part of the key, by
limiting the key to so (say) the first 100 characters, by:
CREATE UNIQUE INDEX `unique_schema_migrations`
ON `schema_migrations` (`version` (100) )
In ActiveRecord 2.1.0 the code which creates the index on the
schema_migrations table is in
connection_adapters/abstract/schema_statements.rb on line 317. This
calls the "add_index" method defined on line 255. The actual sql
statement used to create the index is on line 266. Change this to:
execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)}
ON #{quote_table_name(table_name)} (#{quoted_column_names} (100) )"
ie: add the "(100)" after the column_name, and this will instruct MySQL
to only build the index on the first 100 characters of this column, well
under the 767 byte limit.
The problem is that MySQL has a limit of 767 bytes on the length of
columns used for keys. In UTF8 a varchar(255) consumes 1080 bytes. The
fix is to have the indexing done on a the first part of the key, by
limiting the key to so (say) the first 100 characters, by:
CREATE UNIQUE INDEX `unique_schema_migrations`
ON `schema_migrations` (`version` (100) )
if that were the case, and MySQL required that to be set explicitly,
then surely everyone using rails and utf8 would have this problem.
That doesn't seem to be the case.
CREATE TABLE `schema_migrations` ( `version` varchar(255) NOT
was having trouble with the same issue using Ruby on Rails and thus
used Jon Smillie's idea as well and stuff.. but nothing worked. I
don't know this problem is how old but since I came to this forum so
can someone else therefore here is the detail that I found out:
a. Other than the remedy Jon suggested everything else in his email is
true.
b. Problem exists for UTF 8 (mostly) because every letter is
translated in 3 bytes. Therefore, varchar(255) translate to 765 bytes,
which is okay.
REMEDY
c. If any column in any table of your database has some key set on it
and you have specified the size of that column more than 255 then you
will get this error. The easiest is to keep that size within that
limit i.e. make it 255.
I was having error because 'email' column of one of my table had the
length/size set to 400 characters
Just to add, sadly enough the solution I wrote was true only for MySQL
version 5.0.6+ 'cos on MySQL 6.0 it's still a problem.
On Jul 2, 10:42�am, Matthew Rudy Jacobs <rails-mailing-l...@andreas-
By now, MySQL 6.0.7 and Rails 2.1.2 still have the problem.
Mysql::Error: #42000Specified key was too long; max key length is 767
bytes: CREATE UNIQUE INDEX `unique_schema_migrations` ON
`schema_migrations` (`version`)
Which one should fix the problem? MySQL or Rails team?
This problem blocks Rails' test.
'cos on MySQL 6.0 it's still a problem.