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[close #23009] Limit key length

Mysql has a weird bug where it cannot index a string column of utf8mb4 if it is over a certain character limit. To get compatibility with msql we can add a limit to the key column. 191 characters is a very long key, it seems reasonable to limit across all adapters since using a longer key wouldn't be supported in mysql.

Thanks to @kamipo for the original PR and the test refactoring.

Conversation: https://github.com/rails/rails/pull/23009#issuecomment-171416629
This commit is contained in:
schneems 2016-01-21 11:21:20 -06:00
parent 9a99c7cef5
commit 8897e05ea3
2 changed files with 36 additions and 9 deletions

View file

@ -5,6 +5,10 @@ module ActiveRecord
# This class is used to create a table that keeps track of values and keys such
# as which environment migrations were run in.
class InternalMetadata < ActiveRecord::Base # :nodoc:
# Keys in mysql are limited to 191 characters, due to this no adapter can
# use a longer key
KEY_LIMIT = 191
class << self
def primary_key
"key"
@ -34,10 +38,11 @@ module ActiveRecord
def create_table
unless table_exists?
connection.create_table(table_name, id: false) do |t|
t.column :key, :string
t.column :key, :string, null: false, limit: KEY_LIMIT
t.column :value, :string
t.timestamps
t.index :key, unique: true, name: index_name
t.timestamps
end
end
end

View file

@ -12,9 +12,35 @@ class SchemaMigrationsTest < ActiveRecord::Mysql2TestCase
end
def test_initializes_schema_migrations_for_encoding_utf8mb4
smtn = ActiveRecord::Migrator.schema_migrations_table_name
connection.drop_table smtn, if_exists: true
with_encoding_utf8mb4 do
table_name = ActiveRecord::SchemaMigration.table_name
connection.drop_table table_name, if_exists: true
connection.initialize_schema_migrations_table
assert connection.column_exists?(table_name, :version, :string, collation: 'utf8_general_ci')
end
end
def test_initializes_internal_metadata_for_encoding_utf8mb4
with_encoding_utf8mb4 do
table_name = ActiveRecord::InternalMetadata.table_name
connection.drop_table table_name, if_exists: true
connection.initialize_internal_metadata_table
assert connection.column_exists?(table_name, :key, :string, collation: 'utf8_general_ci')
end
end
def test_key_limit_max_matches_max
assert_equal ActiveRecord::InternalMetadata::KEY_LIMIT ,ActiveRecord::ConnectionAdapters::Mysql2Adapter::MAX_INDEX_LENGTH_FOR_CHARSETS_OF_4BYTES_MAXLEN
end
private
def with_encoding_utf8mb4
database_name = connection.current_database
database_info = connection.select_one("SELECT * FROM information_schema.schemata WHERE schema_name = '#{database_name}'")
@ -23,15 +49,11 @@ class SchemaMigrationsTest < ActiveRecord::Mysql2TestCase
execute("ALTER DATABASE #{database_name} DEFAULT CHARACTER SET utf8mb4")
connection.initialize_schema_migrations_table
limit = ActiveRecord::ConnectionAdapters::AbstractMysqlAdapter::MAX_INDEX_LENGTH_FOR_CHARSETS_OF_4BYTES_MAXLEN
assert connection.column_exists?(smtn, :version, :string, limit: limit)
yield
ensure
execute("ALTER DATABASE #{database_name} DEFAULT CHARACTER SET #{original_charset} COLLATE #{original_collation}")
end
private
def connection
@connection ||= ActiveRecord::Base.connection
end