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Constants
LOST_CONNECTION_ERROR_MESSAGES = [ "Server shutdown in progress", "Broken pipe", "Lost connection to MySQL server during query", "MySQL server has gone away" ]
 
QUOTED_FALSE = '1', '0'
 
NATIVE_DATABASE_TYPES = { :primary_key => "int(11) auto_increment PRIMARY KEY", :string => { :name => "varchar", :limit => 255 }, :text => { :name => "text" }, :integer => { :name => "int", :limit => 4 }, :float => { :name => "float" }, :decimal => { :name => "decimal" }, :datetime => { :name => "datetime" }, :time => { :name => "time" }, :date => { :name => "date" }, :binary => { :name => "blob" }, :boolean => { :name => "tinyint", :limit => 1 } }
 
INDEX_TYPES = [:fulltext, :spatial]
 
INDEX_USINGS = [:btree, :hash]
 
MAX_INDEX_LENGTH_FOR_CHARSETS_OF_4BYTES_MAXLEN = 191
 
CHARSETS_OF_4BYTES_MAXLEN = ['utf8mb4', 'utf16', 'utf16le', 'utf32']
 
Class Public methods
emulate_booleans

By default, the MysqlAdapter will consider all columns of type tinyint(1) as boolean. If you wish to disable this emulation (which was the default behavior in versions 0.13.1 and earlier) you can add the following line to your application.rb file:

ActiveRecord::ConnectionAdapters::Mysql[2]Adapter.emulate_booleans = false
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 195
class_attribute :emulate_booleans
new(connection, logger, connection_options, config)

FIXME: Make the first parameter more similar for the two adapters

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 224
def initialize(connection, logger, connection_options, config)
  super(connection, logger)
  @connection_options, @config = connection_options, config
  @quoted_column_names, @quoted_table_names = {}, {}

  @visitor = Arel::Visitors::MySQL.new self

  if self.class.type_cast_config_to_boolean(config.fetch(:prepared_statements) { true })
    @prepared_statements = true
  else
    @prepared_statements = false
  end
end
Instance Public methods
begin_db_transaction()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 390
def begin_db_transaction
  execute "BEGIN"
end
begin_isolated_db_transaction(isolation)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 394
def begin_isolated_db_transaction(isolation)
  execute "SET TRANSACTION ISOLATION LEVEL #{transaction_isolation_levels.fetch(isolation)}"
  begin_db_transaction
end
case_insensitive_comparison(table, attribute, column, value)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 706
def case_insensitive_comparison(table, attribute, column, value)
  if column.case_sensitive?
    super
  else
    table[attribute].eq(value)
  end
end
case_sensitive_comparison(table, attribute, column, value)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 698
def case_sensitive_comparison(table, attribute, column, value)
  if column.case_sensitive?
    table[attribute].eq(value)
  else
    super
  end
end
case_sensitive_modifier(node, table_attribute)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 693
def case_sensitive_modifier(node, table_attribute)
  node = Arel::Nodes.build_quoted node, table_attribute
  Arel::Nodes::Bin.new(node)
end
change_column_null(table_name, column_name, null, default = nil)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 584
def change_column_null(table_name, column_name, null, default = nil)
  column = column_for(table_name, column_name)

  unless null || default.nil?
    execute("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
  end

  change_column table_name, column_name, column.sql_type, :null => null
end
charset()

Returns the database character set.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 462
def charset
  show_variable 'character_set_database'
end
clear_cache!()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 368
def clear_cache!
  super
  reload_type_map
end
collation()

Returns the database collation strategy.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 467
def collation
  show_variable 'collation_database'
end
column_spec_for_primary_key(column)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 86
def column_spec_for_primary_key(column)
  spec = {}
  if column.auto_increment?
    return unless column.limit == 8
    spec[:id] = ':bigint'
  else
    spec[:id] = column.type.inspect
    spec.merge!(prepare_column_options(column).delete_if { |key, _| [:name, :type, :null].include?(key) })
  end
  spec
end
create_database(name, options = {})

Create a new MySQL database with optional :charset and :collation. Charset defaults to utf8.

Example:

create_database 'charset_test', charset: 'latin1', collation: 'latin1_bin'
create_database 'matt_development'
create_database 'matt_development', charset: :big5
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 441
def create_database(name, options = {})
  if options[:collation]
    execute "CREATE DATABASE `#{name}` DEFAULT CHARACTER SET `#{options[:charset] || 'utf8'}` COLLATE `#{options[:collation]}`"
  else
    execute "CREATE DATABASE `#{name}` DEFAULT CHARACTER SET `#{options[:charset] || 'utf8'}`"
  end
end
current_database()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 457
def current_database
  select_value 'SELECT DATABASE() as db'
end
drop_table(table_name, options = {})
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 565
def drop_table(table_name, options = {})
  execute "DROP#{' TEMPORARY' if options[:temporary]} TABLE#{' IF EXISTS' if options[:if_exists]} #{quote_table_name(table_name)}#{' CASCADE' if options[:force] == :cascade}"
end
empty_insert_statement_value()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 419
def empty_insert_statement_value
  "VALUES ()"
end
execute(sql, name = nil)

Executes the SQL statement in the context of this connection.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 374
def execute(sql, name = nil)
  log(sql, name) { @connection.query(sql) }
end
foreign_keys(table_name)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 608
      def foreign_keys(table_name)
        fk_info = select_all "          SELECT fk.referenced_table_name as 'to_table'
                ,fk.referenced_column_name as 'primary_key'
                ,fk.column_name as 'column'
                ,fk.constraint_name as 'name'
          FROM information_schema.key_column_usage fk
          WHERE fk.referenced_column_name is not null
            AND fk.table_schema = '#{@config[:database]}'
            AND fk.table_name = '#{table_name}'
".strip_heredoc

        create_table_info = select_one("SHOW CREATE TABLE #{quote_table_name(table_name)}")["Create Table"]

        fk_info.map do |row|
          options = {
            column: row['column'],
            name: row['name'],
            primary_key: row['primary_key']
          }

          options[:on_update] = extract_foreign_key_action(create_table_info, row['name'], "UPDATE")
          options[:on_delete] = extract_foreign_key_action(create_table_info, row['name'], "DELETE")

          ForeignKeyDefinition.new(table_name, row['to_table'], options)
        end
      end
index_algorithms()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 295
def index_algorithms
  { default: 'ALGORITHM = DEFAULT', copy: 'ALGORITHM = COPY', inplace: 'ALGORITHM = INPLACE' }
end
initialize_schema_migrations_table()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 240
def initialize_schema_migrations_table
  if CHARSETS_OF_4BYTES_MAXLEN.include?(charset)
    ActiveRecord::SchemaMigration.create_table(MAX_INDEX_LENGTH_FOR_CHARSETS_OF_4BYTES_MAXLEN)
  else
    ActiveRecord::SchemaMigration.create_table
  end
end
native_database_types()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 291
def native_database_types
  NATIVE_DATABASE_TYPES
end
pk_and_sequence_for(table)

Returns a table's primary key and belonging sequence.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 675
def pk_and_sequence_for(table)
  execute_and_free("SHOW CREATE TABLE #{quote_table_name(table)}", 'SCHEMA') do |result|
    create_table = each_hash(result).first[:"Create Table"]
    if create_table.to_s =~ /PRIMARY KEY\s+(?:USING\s+\w+\s+)?\((.+)\)/
      keys = $1.split(",").map { |key| key.delete('`"') }
      keys.length == 1 ? [keys.first, nil] : nil
    else
      nil
    end
  end
end
prepare_column_options(column)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 98
def prepare_column_options(column)
  spec = super
  spec.delete(:precision) if /time/ === column.sql_type && column.precision == 0
  spec.delete(:limit)     if :boolean === column.type
  spec
end
primary_key(table)

Returns just a table's primary key

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 688
def primary_key(table)
  pk_and_sequence = pk_and_sequence_for(table)
  pk_and_sequence && pk_and_sequence.first
end
quoted_false()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 343
def quoted_false
  QUOTED_FALSE
end
quoted_true()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 335
def quoted_true
  QUOTED_TRUE
end
recreate_database(name, options = {})

Drops the database specified on the name attribute and creates it again using the provided options.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 427
def recreate_database(name, options = {})
  drop_database(name)
  sql = create_database(name, options)
  reconnect!
  sql
end
rename_index(table_name, old_name, new_name)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 569
def rename_index(table_name, old_name, new_name)
  if supports_rename_index?
    validate_index_length!(table_name, new_name)

    execute "ALTER TABLE #{quote_table_name(table_name)} RENAME INDEX #{quote_table_name(old_name)} TO #{quote_table_name(new_name)}"
  else
    super
  end
end
rename_table(table_name, new_name)

Renames a table.

Example:

rename_table('octopuses', 'octopi')
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 560
def rename_table(table_name, new_name)
  execute "RENAME TABLE #{quote_table_name(table_name)} TO #{quote_table_name(new_name)}"
  rename_table_indexes(table_name, new_name)
end
schema_creation()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 82
def schema_creation
  SchemaCreation.new self
end
show_variable(name)

SHOW VARIABLES LIKE 'name'

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 669
def show_variable(name)
  variables = select_all("SHOW VARIABLES LIKE '#{name}'", 'SCHEMA')
  variables.first['Value'] unless variables.empty?
end
strict_mode?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 714
def strict_mode?
  self.class.type_cast_config_to_boolean(@config.fetch(:strict, true))
end
supports_datetime_with_precision?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 287
def supports_datetime_with_precision?
  (version[0] == 5 && version[1] >= 6) || version[0] >= 6
end
supports_foreign_keys?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 279
def supports_foreign_keys?
  true
end
supports_index_sort_order?()

Technically MySQL allows to create indexes with the sort order syntax but at the moment (5.5) it doesn't yet implement them

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 263
def supports_index_sort_order?
  true
end
supports_indexes_in_create?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 275
def supports_indexes_in_create?
  true
end
supports_migrations?()

Returns true, since this connection adapter supports migrations.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 249
def supports_migrations?
  true
end
supports_primary_key?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 253
def supports_primary_key?
  true
end
supports_transaction_isolation?()

MySQL 4 technically support transaction isolation, but it is affected by a bug where the transaction level gets persisted for the whole session:

bugs.mysql.com/bug.php?id=39170

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 271
def supports_transaction_isolation?
  version[0] >= 5
end
supports_views?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 283
def supports_views?
  version[0] >= 5
end
table_exists?(name)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 485
def table_exists?(name)
  return false unless name.present?
  return true if tables(nil, nil, name).any?

  name          = name.to_s
  schema, table = name.split('.', 2)

  unless table # A table was provided without a schema
    table  = schema
    schema = nil
  end

  tables(nil, schema, table).any?
end
truncate(table_name, name = nil)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 481
def truncate(table_name, name = nil)
  execute "TRUNCATE TABLE #{quote_table_name(table_name)}", name
end
type_to_sql(type, limit = nil, precision = nil, scale = nil)

Maps logical Rails types to MySQL-specific data types.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 637
def type_to_sql(type, limit = nil, precision = nil, scale = nil)
  case type.to_s
  when 'binary'
    case limit
    when 0..0xfff;           "varbinary(#{limit})"
    when nil;                "blob"
    when 0x1000..0xffffffff; "blob(#{limit})"
    else raise(ActiveRecordError, "No binary type has character length #{limit}")
    end
  when '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
  when 'text'
    case limit
    when 0..0xff;               'tinytext'
    when nil, 0x100..0xffff;    'text'
    when 0x10000..0xffffff;     'mediumtext'
    when 0x1000000..0xffffffff; 'longtext'
    else raise(ActiveRecordError, "No text type has character length #{limit}")
    end
  else
    super
  end
end
unquoted_false()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 347
def unquoted_false
  0
end
unquoted_true()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 339
def unquoted_true
  1
end
valid_type?(type)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 718
def valid_type?(type)
  !native_database_types[type].nil?
end
Instance Protected methods
add_column_sql(table_name, column_name, type, options = {})
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 827
def add_column_sql(table_name, column_name, type, options = {})
  td = create_table_definition(table_name)
  cd = td.new_column_definition(column_name, type, options)
  schema_creation.visit_AddColumn cd
end
add_index_length(option_strings, column_names, options = {})
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 791
def add_index_length(option_strings, column_names, options = {})
  if options.is_a?(Hash) && length = options[:length]
    case length
    when Hash
      column_names.each {|name| option_strings[name] += "(#{length[name]})" if length.has_key?(name) && length[name].present?}
    when Fixnum
      column_names.each {|name| option_strings[name] += "(#{length})"}
    end
  end

  return option_strings
end
add_index_sql(table_name, column_name, options = {})
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 871
def add_index_sql(table_name, column_name, options = {})
  index_name, index_type, index_columns = add_index_options(table_name, column_name, options)
  "ADD #{index_type} INDEX #{index_name} (#{index_columns})"
end
add_timestamps_sql(table_name, options = {})
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 881
def add_timestamps_sql(table_name, options = {})
  [add_column_sql(table_name, :created_at, :datetime, options), add_column_sql(table_name, :updated_at, :datetime, options)]
end
change_column_sql(table_name, column_name, type, options = {})
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 833
def change_column_sql(table_name, column_name, type, options = {})
  column = column_for(table_name, column_name)

  unless options_include_default?(options)
    options[:default] = column.default
  end

  unless options.has_key?(:null)
    options[:null] = column.null
  end

  td = create_table_definition(table_name)
  cd = td.new_column_definition(column.name, type, options)
  schema_creation.accept(ChangeColumnDefinition.new(cd, column.name))
end
extract_precision(sql_type)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 768
def extract_precision(sql_type)
  if /time/ === sql_type
    super || 0
  else
    super
  end
end
fetch_type_metadata(sql_type, collation = "", extra = "")
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 776
def fetch_type_metadata(sql_type, collation = "", extra = "")
  MysqlTypeMetadata.new(super(sql_type), collation: collation, extra: extra, strict: strict_mode?)
end
quoted_columns_for_index(column_names, options = {})
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 804
def quoted_columns_for_index(column_names, options = {})
  option_strings = Hash[column_names.map {|name| [name, '']}]

  # add index length
  option_strings = add_index_length(option_strings, column_names, options)

  # add index sort order
  option_strings = add_index_sort_order(option_strings, column_names, options)

  column_names.map {|name| quote_column_name(name) + option_strings[name]}
end
remove_column_sql(table_name, column_name, type = nil, options = {})
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 863
def remove_column_sql(table_name, column_name, type = nil, options = {})
  "DROP #{quote_column_name(column_name)}"
end
remove_columns_sql(table_name, *column_names)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 867
def remove_columns_sql(table_name, *column_names)
  column_names.map {|column_name| remove_column_sql(table_name, column_name) }
end
remove_index_sql(table_name, options = {})
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 876
def remove_index_sql(table_name, options = {})
  index_name = index_name_for_remove(table_name, options)
  "DROP INDEX #{index_name}"
end
remove_timestamps_sql(table_name, options = {})
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 885
def remove_timestamps_sql(table_name, options = {})
  [remove_column_sql(table_name, :updated_at), remove_column_sql(table_name, :created_at)]
end
rename_column_sql(table_name, column_name, new_column_name)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 849
def rename_column_sql(table_name, column_name, new_column_name)
  column  = column_for(table_name, column_name)
  options = {
    default: column.default,
    null: column.null,
    auto_increment: column.auto_increment?
  }

  current_type = select_one("SHOW COLUMNS FROM #{quote_table_name(table_name)} LIKE '#{column_name}'", 'SCHEMA')["Type"]
  td = create_table_definition(table_name)
  cd = td.new_column_definition(new_column_name, current_type, options)
  schema_creation.accept(ChangeColumnDefinition.new(cd, column.name))
end
subquery_for(key, select)

MySQL is too stupid to create a temporary table for use subquery, so we have to give it some prompting in the form of a subsubquery. Ugh!

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 782
def subquery_for(key, select)
  subsubselect = select.clone
  subsubselect.projections = [key]

  subselect = Arel::SelectManager.new(select.engine)
  subselect.project Arel.sql(key.name)
  subselect.from subsubselect.as('__active_record_temp')
end
translate_exception(exception, message)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 816
def translate_exception(exception, message)
  case error_number(exception)
  when 1062
    RecordNotUnique.new(message, exception)
  when 1452
    InvalidForeignKey.new(message, exception)
  else
    super
  end
end