module ActiveRecord::ConnectionAdapters::PostgreSQL::Utils

def extract_schema_qualified_name(string)

* "schema.name"."table name"
* "schema_name".table_name
* schema_name."table.name"
* schema_name.table_name
* "table.name"
* table_name

+string+ supports the range of schema/table references understood by PostgreSQL, for example:
+schema+ and +identifier+ exclude surrounding quotes (regardless of whether provided in +string+)
+schema+ is +nil+ if not specified in +string+.
extracted from +string+.
Returns an instance of ActiveRecord::ConnectionAdapters::PostgreSQL::Name 
def extract_schema_qualified_name(string)
  schema, table = string.scan(/[^".]+|"[^"]*"/)
  if table.nil?
    table = schema
    schema = nil
  end
  PostgreSQL::Name.new(schema, table)
end

def unquote_identifier(identifier) 

def unquote_identifier(identifier)
  if identifier && identifier.start_with?('"')
    identifier[1..-2]
  else
    identifier
  end
end