Module: ActiveRecord::ConnectionAdapters::SchemaStatements

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1545

def use_foreign_keys?
  supports_foreign_keys? && foreign_keys_enabled?
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1293

def add_check_constraint(table_name, expression, if_not_exists: false, **options)
  return unless supports_check_constraints?

  options = check_constraint_options(table_name, expression, options)
  return if if_not_exists && check_constraint_exists?(table_name, **options)

  at = create_alter_table(table_name)
  at.add_check_constraint(expression, options)

  execute schema_creation.accept(at)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 636

def add_column(table_name, column_name, type, **options)
  add_column_def = build_add_column_definition(table_name, column_name, type, **options)
  return unless add_column_def

  execute schema_creation.accept(add_column_def)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1837

def add_column_for_alter(table_name, column_name, type, **options)
  td = create_table_definition(table_name)
  cd = td.new_column_definition(column_name, type, **options)
  schema_creation.accept(AddColumnDefinition.new(cd))
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 643

def add_columns(table_name, *column_names, type:, **options) # :nodoc:
  column_names.each do |column_name|
    add_column(table_name, column_name, type, **options)
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1173

def add_foreign_key(from_table, to_table, **options)
  return unless use_foreign_keys?
  return if options[:if_not_exists] == true && foreign_key_exists?(from_table, to_table, **options.slice(:column))

  options = foreign_key_options(from_table, to_table, options)
  at = create_alter_table from_table
  at.add_foreign_key to_table, options

  execute schema_creation.accept(at)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 915

def add_index(table_name, column_name, **options)
  create_index = build_create_index_definition(table_name, column_name, **options)
  execute schema_creation.accept(create_index)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1476

def add_index_options(table_name, column_name, name: nil, if_not_exists: false, internal: false, **options) # :nodoc:
  options.assert_valid_keys(:unique, :length, :order, :opclass, :where, :type, :using, :comment, :algorithm, :include, :nulls_not_distinct)

  column_names = index_column_names(column_name)

  index_name = name&.to_s
  index_name ||= index_name(table_name, column_names)

  validate_index_length!(table_name, index_name, internal)

  index = IndexDefinition.new(
    table_name, index_name,
    options[:unique],
    column_names,
    lengths: options[:length] || {},
    orders: options[:order] || {},
    opclasses: options[:opclass] || {},
    where: options[:where],
    type: options[:type],
    using: options[:using],
    include: options[:include],
    nulls_not_distinct: options[:nulls_not_distinct],
    comment: options[:comment]
  )

  [index, index_algorithm(options[:algorithm]), if_not_exists]
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1622

def add_index_sort_order(quoted_columns, **options)
  orders = options_for_index_columns(options[:order])
  quoted_columns.each do |name, column|
    column << " #{orders[name].upcase}" if orders[name].present?
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1639

def add_options_for_index_columns(quoted_columns, **options)
  if supports_index_sort_order?
    quoted_columns = add_index_sort_order(quoted_columns, **options)
  end

  quoted_columns
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1063

def add_reference(table_name, ref_name, **options)
  ReferenceDefinition.new(ref_name, **options).add(table_name, self)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1459

def add_timestamps(table_name, **options)
  fragments = add_timestamps_for_alter(table_name, **options)
  execute "ALTER TABLE #{quote_table_name(table_name)} #{fragments.join(', ')}"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1860

def add_timestamps_for_alter(table_name, **options)
  options[:null] = false if options[:null].nil?

  if !options.key?(:precision) && supports_datetime_with_precision?
    options[:precision] = 6
  end

  [
    add_column_for_alter(table_name, :created_at, :datetime, **options),
    add_column_for_alter(table_name, :updated_at, :datetime, **options)
  ]
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1364

def assume_migrated_upto_version(version)
  version = version.to_i
  sm_table = quote_table_name(pool.schema_migration.table_name)

  migration_context = pool.migration_context
  migrated = migration_context.get_all_versions
  versions = migration_context.migrations.map(&:version)

  unless migrated.include?(version)
    execute "INSERT INTO #{sm_table} (version) VALUES (#{quote(version)})"
  end

  inserting = (versions - migrated).select { |v| v < version }
  if inserting.any?
    if (duplicate = inserting.detect { |v| inserting.count(v) > 1 })
      raise "Duplicate migration #{duplicate}. Please renumber your migrations to resolve the conflict."
    end
    execute insert_versions_sql(inserting)
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 654

def build_add_column_definition(table_name, column_name, type, **options) # :nodoc:
  return if options[:if_not_exists] == true && column_exists?(table_name, column_name)

  if supports_datetime_with_precision?
    if type == :datetime && !options.key?(:precision)
      options[:precision] = 6
    end
  end

  alter_table = create_alter_table(table_name)
  alter_table.add_column(column_name, type, **options)
  alter_table
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 738

def build_change_column_default_definition(table_name, column_name, default_or_changes) # :nodoc:
  raise NotImplementedError, "build_change_column_default_definition is not implemented"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 925

def build_create_index_definition(table_name, column_name, **options) # :nodoc:
  index, algorithm, if_not_exists = add_index_options(table_name, column_name, **options)
  CreateIndexDefinition.new(index, algorithm, if_not_exists)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 408

def build_create_join_table_definition(table_1, table_2, column_options: {}, **options) # :nodoc:
  join_table_name = find_join_table_name(table_1, table_2, options)
  column_options.reverse_merge!(null: false, index: false)

  t1_ref, t2_ref = [table_1, table_2].map { |t| reference_name_for_table(t) }

  build_create_table_definition(join_table_name, **options.merge!(id: false)) do |td|
    td.references t1_ref, **column_options
    td.references t2_ref, **column_options
    yield td if block_given?
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 333

def build_create_table_definition(table_name, id: :primary_key, primary_key: nil, force: nil, **options)
  table_definition = create_table_definition(table_name, **options.extract!(*valid_table_definition_options, :_skip_validate_options))
  table_definition.set_primary_key(table_name, id, primary_key, **options.extract!(*valid_primary_key_options, :_skip_validate_options))

  yield table_definition if block_given?

  table_definition
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1555

def bulk_change_table(table_name, operations) # :nodoc:
  sql_fragments = []
  non_combinable_operations = []

  operations.each do |command, args|
    table, arguments = args.shift, args
    method = :"#{command}_for_alter"

    if respond_to?(method, true)
      sqls, procs = Array(send(method, table, *arguments)).partition { |v| v.is_a?(String) }
      sql_fragments.concat(sqls)
      non_combinable_operations.concat(procs)
    else
      execute "ALTER TABLE #{quote_table_name(table_name)} #{sql_fragments.join(", ")}" unless sql_fragments.empty?
      non_combinable_operations.each(&:call)
      sql_fragments = []
      non_combinable_operations = []
      send(command, table, *arguments)
    end
  end

  execute "ALTER TABLE #{quote_table_name(table_name)} #{sql_fragments.join(", ")}" unless sql_fragments.empty?
  non_combinable_operations.each(&:call)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1829

def can_remove_index_by_name?(column_name, options)
  column_name.nil? && options.key?(:name) && options.except(:name, :algorithm).empty?
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 711

def change_column(table_name, column_name, type, **options)
  raise NotImplementedError, "change_column is not implemented"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1537

def change_column_comment(table_name, column_name, comment_or_changes)
  raise NotImplementedError, "#{self.class} does not support changing column comments"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 729

def change_column_default(table_name, column_name, default_or_changes)
  raise NotImplementedError, "change_column_default is not implemented"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1843

def change_column_default_for_alter(table_name, column_name, default_or_changes)
  cd = build_change_column_default_definition(table_name, column_name, default_or_changes)
  schema_creation.accept(cd)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 758

def change_column_null(table_name, column_name, null, default = nil)
  raise NotImplementedError, "change_column_null is not implemented"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 510

def change_table(table_name, base = self, **options)
  if supports_bulk_alter? && options[:bulk]
    recorder = ActiveRecord::Migration::CommandRecorder.new(self)
    yield update_table_definition(table_name, recorder)
    bulk_change_table(table_name, recorder.commands)
  else
    yield update_table_definition(table_name, base)
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1527

def change_table_comment(table_name, comment_or_changes)
  raise NotImplementedError, "#{self.class} does not support changing table comments"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1341

def check_constraint_exists?(table_name, **options)
  if !options.key?(:name) && !options.key?(:expression)
    raise ArgumentError, "At least one of :name or :expression must be supplied"
  end
  check_constraint_for(table_name, **options).present?
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1797

def check_constraint_for(table_name, **options)
  return unless supports_check_constraints?
  chk_name = check_constraint_name(table_name, **options)
  check_constraints(table_name).detect { |chk| chk.defined_for?(name: chk_name, **options) }
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1803

def check_constraint_for!(table_name, expression: nil, **options)
  check_constraint_for(table_name, expression: expression, **options) ||
    raise(ArgumentError, "Table '#{table_name}' has no check constraint for #{expression || options}")
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1787

def check_constraint_name(table_name, **options)
  options.fetch(:name) do
    expression = options.fetch(:expression)
    identifier = "#{table_name}_#{expression}_chk"
    hashed_identifier = OpenSSL::Digest::SHA256.hexdigest(identifier).first(10)

    "chk_rails_#{hashed_identifier}"
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1305

def check_constraint_options(table_name, expression, options) # :nodoc:
  options = options.dup
  options[:name] ||= check_constraint_name(table_name, expression: expression, **options)
  options
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1273

def check_constraints(table_name)
  raise NotImplementedError
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 132

def column_exists?(table_name, column_name, type = nil, **options)
  column_name = column_name.to_s
  checks = []
  checks << lambda { |c| c.name == column_name }
  checks << lambda { |c| c.type == type.to_sym rescue nil } if type
  column_options_keys.each do |attr|
    checks << lambda { |c| c.send(attr) == options[attr] } if options.key?(attr)
  end

  columns(table_name).any? { |c| checks.all? { |check| check[c] } }
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1618

def column_options_keys
  [:limit, :precision, :scale, :default, :null, :collation, :comment]
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 107

def columns(table_name)
  table_name = table_name.to_s
  definitions = column_definitions(table_name)
  definitions.map do |field|
    new_column_from_field(table_name, field, definitions)
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1425

def columns_for_distinct(columns, orders) # :nodoc:
  columns
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1705

def create_alter_table(name)
  AlterTable.new create_table_definition(name)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 389

def create_join_table(table_1, table_2, column_options: {}, **options)
  join_table_name = find_join_table_name(table_1, table_2, options)

  column_options.reverse_merge!(null: false, index: false)

  t1_ref, t2_ref = [table_1, table_2].map { |t| reference_name_for_table(t) }

  create_table(join_table_name, **options.merge!(id: false)) do |td|
    td.references t1_ref, **column_options
    td.references t2_ref, **column_options
    yield td if block_given?
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1541

def create_schema_dumper(options) # :nodoc:
  SchemaDumper.create(self, options)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 293

def create_table(table_name, id: :primary_key, primary_key: nil, force: nil, **options, &block)
  validate_create_table_options!(options)
  validate_table_length!(table_name) unless options[:_uses_legacy_table_name]

  if force && options.key?(:if_not_exists)
    raise ArgumentError, "Options `:force` and `:if_not_exists` cannot be used simultaneously."
  end

  td = build_create_table_definition(table_name, id: id, primary_key: primary_key, force: force, **options, &block)

  if force
    drop_table(table_name, force: force, if_exists: true)
  else
    schema_cache.clear_data_source_cache!(table_name.to_s)
  end

  result = execute schema_creation.accept(td)

  unless supports_indexes_in_create?
    td.indexes.each do |column_name, index_options|
      add_index(table_name, column_name, **index_options, if_not_exists: td.if_not_exists)
    end
  end

  if supports_comments? && !supports_comments_in_create?
    if table_comment = td.comment.presence
      change_table_comment(table_name, table_comment)
    end

    td.columns.each do |column|
      change_column_comment(table_name, column.name, column.comment) if column.comment.present?
    end
  end

  result
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1701

def create_table_definition(name, **options)
  TableDefinition.new(self, name, **options)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 44

def data_source_exists?(name)
  query_values(data_source_sql(name), "SCHEMA").any? if name.present?
rescue NotImplementedError
  data_sources.include?(name.to_s)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1890

def data_source_sql(name = nil, type: nil)
  raise NotImplementedError
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 34

def data_sources
  query_values(data_source_sql, "SCHEMA")
rescue NotImplementedError
  tables | views
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1429

def distinct_relation_for_primary_key(relation) # :nodoc:
  primary_key_columns = Array(relation.primary_key).map do |column|
    visitor.compile(relation.table[column])
  end

  values = columns_for_distinct(
    primary_key_columns,
    relation.order_values
  )

  limited = relation.reselect(values).distinct!
  limited_ids = select_rows(limited.arel, "SQL").map do |results|
    results.last(Array(relation.primary_key).length) # ignores order values for MySQL and PostgreSQL
  end

  if limited_ids.empty?
    relation.none!
  else
    relation.where!(**Array(relation.primary_key).zip(limited_ids.transpose).to_h)
  end

  relation.limit_value = relation.offset_value = nil
  relation
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 427

def drop_join_table(table_1, table_2, **options)
  join_table_name = find_join_table_name(table_1, table_2, options)
  drop_table(join_table_name, **options)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 540

def drop_table(*table_names, **options)
  table_names.each do |table_name|
    schema_cache.clear_data_source_cache!(table_name.to_s)
    execute "DROP TABLE#{' IF EXISTS' if options[:if_exists]} #{quote_table_name(table_name)}"
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1355

def dump_schema_information # :nodoc:
  versions = pool.schema_migration.versions
  insert_versions_sql(versions) if versions.any?
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1745

def expression_column_name?(column_name)
  column_name.is_a?(String) && /\W/.match?(column_name)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1775

def extract_foreign_key_action(specifier)
  case specifier
  when "CASCADE"; :cascade
  when "SET NULL"; :nullify
  when "RESTRICT"; :restrict
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1827

alias :extract_new_comment_value :extract_new_default_value

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1820

def extract_new_default_value(default_or_changes)
  if default_or_changes.is_a?(Hash) && default_or_changes.has_key?(:from) && default_or_changes.has_key?(:to)
    default_or_changes[:to]
  else
    default_or_changes
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1717

def fetch_type_metadata(sql_type)
  cast_type = lookup_cast_type(sql_type)
  SqlTypeMetadata.new(
    sql_type: sql_type,
    type: cast_type.type,
    limit: cast_type.limit,
    precision: cast_type.precision,
    scale: cast_type.scale,
  )
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1241

def foreign_key_column_for(table_name, column_name) # :nodoc:
  name = strip_table_name_prefix_and_suffix(table_name)
  "#{name.singularize}_#{column_name}"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1237

def foreign_key_exists?(from_table, to_table = nil, **options)
  foreign_key_for(from_table, to_table: to_table, **options).present?
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1765

def foreign_key_for(from_table, **options)
  return unless use_foreign_keys?
  foreign_keys(from_table).detect { |fk| fk.defined_for?(**options) }
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1770

def foreign_key_for!(from_table, to_table: nil, **options)
  foreign_key_for(from_table, to_table: to_table, **options) ||
    raise(ArgumentError, "Table '#{from_table}' has no foreign key for #{to_table || options}")
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1755

def foreign_key_name(table_name, options)
  options.fetch(:name) do
    columns = Array(options.fetch(:column)).map(&:to_s)
    identifier = "#{table_name}_#{columns * '_and_'}_fk"
    hashed_identifier = OpenSSL::Digest::SHA256.hexdigest(identifier).first(10)

    "fk_rails_#{hashed_identifier}"
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1246

def foreign_key_options(from_table, to_table, options) # :nodoc:
  options = options.dup

  if options[:primary_key].is_a?(Array)
    options[:column] ||= options[:primary_key].map do |pk_column|
      foreign_key_column_for(to_table, pk_column)
    end
  else
    options[:column] ||= foreign_key_column_for(to_table, "id")
  end

  options[:name]   ||= foreign_key_name(from_table, options)

  if options[:column].is_a?(Array) || options[:primary_key].is_a?(Array)
    if Array(options[:primary_key]).size != Array(options[:column]).size
      raise ArgumentError, <<~MSG.squish
        For composite primary keys, specify :column and :primary_key, where
        :column must reference all the :primary_key columns from #{to_table.inspect}
      MSG
    end
  end

  options
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1103

def foreign_keys(table_name)
  raise NotImplementedError, "foreign_keys is not implemented"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1598

def generate_index_name(table_name, column)
  name = "index_#{table_name}_on_#{Array(column) * '_and_'}"
  return name if name.bytesize <= max_index_name_size

  # Fallback to short version, add hash to ensure uniqueness
  hashed_identifier = "_" + OpenSSL::Digest::SHA256.hexdigest(name).first(10)
  name = "idx_on_#{Array(column) * '_'}"

  short_limit = max_index_name_size - hashed_identifier.bytesize
  short_name = name.mb_chars.limit(short_limit).to_s

  "#{short_name}#{hashed_identifier}"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1504

def index_algorithm(algorithm) # :nodoc:
  index_algorithms.fetch(algorithm) do
    raise ArgumentError, "Algorithm must be one of the following: #{index_algorithms.keys.map(&:inspect).join(', ')}"
  end if algorithm
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1728

def index_column_names(column_names)
  if expression_column_name?(column_names)
    column_names
  else
    Array(column_names)
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 102

def index_exists?(table_name, column_name, **options)
  indexes(table_name).any? { |i| i.defined_for?(column_name, **options) }
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 992

def index_name(table_name, options) # :nodoc:
  if Hash === options
    if options[:column]
      if options[:_uses_legacy_index_name]
        "index_#{table_name}_on_#{Array(options[:column]) * '_and_'}"
      else
        generate_index_name(table_name, options[:column])
      end
    elsif options[:name]
      options[:name]
    else
      raise ArgumentError, "You must specify the index name"
    end
  else
    index_name(table_name, index_name_options(options))
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1011

def index_name_exists?(table_name, index_name)
  index_name = index_name.to_s
  indexes(table_name).detect { |i| i.name == index_name }
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1647

def index_name_for_remove(table_name, column_name, options)
  return options[:name] if can_remove_index_by_name?(column_name, options)

  checks = []

  if !options.key?(:name) && expression_column_name?(column_name)
    options[:name] = index_name(table_name, column_name)
    column_names = []
  else
    column_names = index_column_names(column_name || options[:column])
  end

  checks << lambda { |i| i.name == options[:name].to_s } if options.key?(:name)

  if column_names.present? && !(options.key?(:name) && expression_column_name?(column_names))
    checks << lambda { |i| index_name(table_name, i.columns) == index_name(table_name, column_names) }
  end

  raise ArgumentError, "No name or columns specified" if checks.none?

  matching_indexes = indexes(table_name).select { |i| checks.all? { |check| check[i] } }

  if matching_indexes.count > 1
    raise ArgumentError, "Multiple indexes found on #{table_name} columns #{column_names}. " \
      "Specify an index name from #{matching_indexes.map(&:name).join(', ')}"
  elsif matching_indexes.none?
    raise ArgumentError, "No indexes found on #{table_name} with the options provided."
  else
    matching_indexes.first.name
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1736

def index_name_options(column_names)
  if expression_column_name?(column_names)
    column_names = column_names.scan(/\w+/).join("_")
  end

  { column: column_names }
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 81

def indexes(table_name)
  raise NotImplementedError, "#indexes is not implemented"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1877

def insert_versions_sql(versions)
  sm_table = quote_table_name(pool.schema_migration.table_name)

  if versions.is_a?(Array)
    sql = +"INSERT INTO #{sm_table} (version) VALUES\n"
    sql << versions.reverse.map { |v| "(#{quote(v)})" }.join(",\n")
    sql << ";"
    sql
  else
    "INSERT INTO #{sm_table} (version) VALUES (#{quote(versions)});"
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1360

def internal_string_options_for_primary_key # :nodoc:
  { primary_key: true }
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1593

def max_index_name_size
  62
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 14

def native_database_types
  {}
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1629

def options_for_index_columns(options)
  if options.is_a?(Hash)
    options.symbolize_keys
  else
    Hash.new { |hash, column| hash[column] = options }
  end
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1517

def options_include_default?(options)
  options.include?(:default) && !(options[:null] == false && options[:default].nil?)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 145

def primary_key(table_name)
  pk = primary_keys(table_name)
  pk = pk.first unless pk.size > 1
  pk
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1510

def quoted_columns_for_index(column_names, options) # :nodoc:
  quoted_columns = column_names.each_with_object({}) do |name, result|
    result[name.to_sym] = quote_column_name(name).dup
  end
  add_options_for_index_columns(quoted_columns, **options).values.join(", ")
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1894

def quoted_scope(name = nil, type: nil)
  raise NotImplementedError
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1833

def reference_name_for_table(table_name)
  table_name.to_s.singularize
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1099

alias :remove_belongs_to :remove_reference

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1324

def remove_check_constraint(table_name, expression = nil, if_exists: false, **options)
  return unless supports_check_constraints?

  return if if_exists && !check_constraint_exists?(table_name, **options)

  chk_name_to_delete = check_constraint_for!(table_name, expression: expression, **options).name

  at = create_alter_table(table_name)
  at.drop_check_constraint(chk_name_to_delete)

  execute schema_creation.accept(at)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 699

def remove_column(table_name, column_name, type = nil, **options)
  return if options[:if_exists] == true && !column_exists?(table_name, column_name)

  execute "ALTER TABLE #{quote_table_name(table_name)} #{remove_column_for_alter(table_name, column_name, type, **options)}"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1852

def remove_column_for_alter(table_name, column_name, type = nil, **options)
  "DROP COLUMN #{quote_column_name(column_name)}"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 675

def remove_columns(table_name, *column_names, type: nil, **options)
  if column_names.empty?
    raise ArgumentError.new("You must specify at least one column name. Example: remove_columns(:people, :first_name)")
  end

  remove_column_fragments = remove_columns_for_alter(table_name, *column_names, type: type, **options)
  execute "ALTER TABLE #{quote_table_name(table_name)} #{remove_column_fragments.join(', ')}"
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1856

def remove_columns_for_alter(table_name, *column_names, **options)
  column_names.map { |column_name| remove_column_for_alter(table_name, column_name) }
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1348

def remove_constraint(table_name, constraint_name) # :nodoc:
  at = create_alter_table(table_name)
  at.drop_constraint(constraint_name)

  execute schema_creation.accept(at)
end

# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 1214

def remove_foreign_key(from_table, to_table = nil, **options)
  return unless use_foreign_keys?
  return if options.delete(:if_exists) == true && !foreign_key_exists?(from_table, to_table)

  fk_name_to_delete = foreign_key_for!(from_table, to_table: to_table, **options).name

  at = create_alter_table from_table
  at.drop_foreign_key fk_name_to_delete

  execute schema_creation.accept(at)
end