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Constants
CHARSETS_OF_4BYTES_MAXLEN = ["utf8mb4", "utf16", "utf16le", "utf32"]
 
ER_DUP_ENTRY = 1062
 

See dev.mysql.com/doc/refman/5.7/en/error-messages-server.html

ER_NOT_NULL_VIOLATION = 1048
 
ER_DO_NOT_HAVE_DEFAULT = 1364
 
ER_NO_REFERENCED_ROW_2 = 1452
 
ER_DATA_TOO_LONG = 1406
 
ER_OUT_OF_RANGE = 1264
 
ER_LOCK_DEADLOCK = 1213
 
ER_CANNOT_ADD_FOREIGN = 1215
 
ER_CANNOT_CREATE_TABLE = 1005
 
Class Public methods
new(connection, logger, connection_options, config)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 65
def initialize(connection, logger, connection_options, config)
  super(connection, logger, config)

  @statements = StatementPool.new(self.class.type_cast_config_to_integer(config[:statement_limit]))

  if version < "5.1.10"
    raise "Your version of MySQL (#{full_version.match(/^\d+\.\d+\.\d+/)[0]}) is too old. Active Record supports MySQL >= 5.1.10."
  end
end
Instance Public methods
begin_db_transaction()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 232
def begin_db_transaction
  execute "BEGIN"
end
begin_isolated_db_transaction(isolation)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 236
def begin_isolated_db_transaction(isolation)
  execute "SET TRANSACTION ISOLATION LEVEL #{transaction_isolation_levels.fetch(isolation)}"
  begin_db_transaction
end
case_sensitive_comparison(table, attribute, column, value)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 614
def case_sensitive_comparison(table, attribute, column, value)
  if column.collation && !column.case_sensitive?
    table[attribute].eq(Arel::Nodes::Bin.new(Arel::Nodes::BindParam.new))
  else
    super
  end
end
charset()

Returns the database character set.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 304
def charset
  show_variable "character_set_database"
end
clear_cache!()

Clears the prepared statements cache.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 198
def clear_cache!
  reload_type_map
  @statements.clear
end
collation()

Returns the database collation strategy.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 309
def collation
  show_variable "collation_database"
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 283
def create_database(name, options = {})
  if options[:collation]
    execute "CREATE DATABASE #{quote_table_name(name)} DEFAULT CHARACTER SET #{quote_table_name(options[:charset] || 'utf8')} COLLATE #{quote_table_name(options[:collation])}"
  else
    execute "CREATE DATABASE #{quote_table_name(name)} DEFAULT CHARACTER SET #{quote_table_name(options[:charset] || 'utf8')}"
  end
end
current_database()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 299
def current_database
  select_value "SELECT DATABASE() as db"
end
drop_table(table_name, options = {})

Drops a table from the database.

:force

Set to :cascade to drop dependent objects as well. Defaults to false.

:if_exists

Set to true to only drop the table if it exists. Defaults to false.

:temporary

Set to true to drop temporary table. Defaults to false.

Although this command ignores most options and the block if one is given, it can be helpful to provide these in a migration's change method so it can be reverted. In that case, options and the block will be used by create_table.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 462
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 261
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 217
def execute(sql, name = nil)
  log(sql, name) do
    ActiveSupport::Dependencies.interlock.permit_concurrent_loads do
      @connection.query(sql)
    end
  end
end
explain(arel, binds = [])
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 207
def explain(arel, binds = [])
  sql     = "EXPLAIN #{to_sql(arel, binds)}"
  start   = Time.now
  result  = exec_query(sql, "EXPLAIN", binds)
  elapsed = Time.now - start

  MySQL::ExplainPrettyPrinter.new.pp(result, elapsed)
end
foreign_keys(table_name)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 512
      def foreign_keys(table_name)
        raise ArgumentError unless table_name.present?

        schema, name = extract_schema_qualified_name(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',
                 rc.update_rule AS 'on_update',
                 rc.delete_rule AS 'on_delete'
          FROM information_schema.key_column_usage fk
          JOIN information_schema.referential_constraints rc
          USING (constraint_schema, constraint_name)
          WHERE fk.referenced_column_name IS NOT NULL
            AND fk.table_schema = #{quote(schema)}
            AND fk.table_name = #{quote(name)}
            AND rc.table_name = #{quote(name)}
".strip_heredoc, "SCHEMA")

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

          options[:on_update] = extract_foreign_key_action(row["on_update"])
          options[:on_delete] = extract_foreign_key_action(row["on_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 160
def index_algorithms
  { default: "ALGORITHM = DEFAULT", copy: "ALGORITHM = COPY", inplace: "ALGORITHM = INPLACE" }
end
native_database_types()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 156
def native_database_types
  NATIVE_DATABASE_TYPES
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 269
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 466
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 442
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
show_variable(name)

SHOW VARIABLES LIKE 'name'

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 593
def show_variable(name)
  select_value("SELECT @@#{name}", "SCHEMA")
rescue ActiveRecord::StatementInvalid
  nil
end
strict_mode?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 642
def strict_mode?
  self.class.type_cast_config_to_boolean(@config.fetch(:strict, true))
end
supports_advisory_locks?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 144
def supports_advisory_locks?
  true
end
supports_datetime_with_precision?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 136
def supports_datetime_with_precision?
  if mariadb?
    version >= "5.3.0"
  else
    version >= "5.6.4"
  end
end
supports_explain?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 120
def supports_explain?
  true
end
supports_foreign_keys?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 128
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 112
def supports_index_sort_order?
  true
end
supports_indexes_in_create?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 124
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 92
def supports_migrations?
  true
end
supports_primary_key?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 96
def supports_primary_key?
  true
end
supports_statement_cache?()

Returns true, since this connection adapter supports prepared statement caching.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 106
def supports_statement_cache?
  true
end
supports_transaction_isolation?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 116
def supports_transaction_isolation?
  true
end
supports_views?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 132
def supports_views?
  true
end
truncate(table_name, name = nil)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 364
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, unsigned = nil)

Maps logical Rails types to MySQL-specific data types.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 569
def type_to_sql(type, limit = nil, precision = nil, scale = nil, unsigned = nil)
  sql =            case type.to_s
    when "integer"
      integer_to_sql(limit)
    when "text"
      text_to_sql(limit)
    when "blob"
      binary_to_sql(limit)
    when "binary"
      if (0..0xfff) === limit
        "varbinary(#{limit})"
      else
        binary_to_sql(limit)
      end
    else
      super(type, limit, precision, scale)
    end

  sql << " unsigned" if unsigned && type != :primary_key
  sql
end
valid_type?(type)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 646
def valid_type?(type)
  !native_database_types[type].nil?
end