hacken-in/hacken-in

#
# Monkey-patch the refused Rails 4.2 patch at https://github.com/rails/rails/pull/31330
#
# Updates sequence logic to support PostgreSQL 10.
#
# TODO: Remvoe when upgrading to Rails 5

module ActiveRecord
    module ConnectionAdapters
        module PostgreSQL
            module SchemaStatements
                # Resets the sequence of a table's primary key to the maximum value.
                def reset_pk_sequence!(table, pk = nil, sequence = nil) #:nodoc:
                    unless pk and sequence
                        default_pk, default_sequence = pk_and_sequence_for(table)

                        pk ||= default_pk
                        sequence ||= default_sequence
                    end

                    if @logger && pk && !sequence
                        @logger.warn "#{table} has primary key #{pk} with no default sequence"
                    end

                    if pk && sequence
                        quoted_sequence = quote_table_name(sequence)
                        max_pk = select_value("SELECT MAX(#{quote_column_name pk}) FROM #{quote_table_name(table)}")
                        if max_pk.nil?
                            if postgresql_version >= 100000
                                minvalue = select_value("SELECT seqmin FROM pg_sequence WHERE seqrelid = #{quote(quoted_sequence)}::regclass")
                            else
                                minvalue = select_value("SELECT min_value FROM #{quoted_sequence}")
                            end
                        end

                        select_value <<-end_sql, 'SCHEMA'
                        SELECT setval(#{quote(quoted_sequence)}, #{max_pk ? max_pk : minvalue}, #{max_pk ? true : false})
                                                    end_sql
                    end
                end
            end
        end
    end
end