Active Record PostgreSQL 适配器 Alter Table

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb, line 341
def initialize(td)
  super
  @constraint_validations = []
  @exclusion_constraint_adds = []
  @exclusion_constraint_drops = []
  @unique_constraint_adds = []
  @unique_constraint_drops = []
end

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb, line 354
def add_exclusion_constraint(expression, options)
  @exclusion_constraint_adds << @td.new_exclusion_constraint_definition(expression, options)
end

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb, line 362
def add_unique_constraint(column_name, options)
  @unique_constraint_adds << @td.new_unique_constraint_definition(column_name, options)
end

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb, line 358
def drop_exclusion_constraint(constraint_name)
  @exclusion_constraint_drops << constraint_name
end

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb, line 366
def drop_unique_constraint(unique_constraint_name)
  @unique_constraint_drops << unique_constraint_name
end

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb, line 350
def validate_constraint(name)
  @constraint_validations << name
end