def change_column(table_name, column_name, type, options = {})
quoted_table_name = quote_table_name(table_name)
begin
execute "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quote_column_name(column_name)} TYPE #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
rescue ActiveRecord::StatementInvalid => e
raise e if postgresql_version > 80000
begin
begin_db_transaction
tmp_column_name = "#{column_name}_ar_tmp"
add_column(table_name, tmp_column_name, type, options)
execute "UPDATE #{quoted_table_name} SET #{quote_column_name(tmp_column_name)} = CAST(#{quote_column_name(column_name)} AS #{type_to_sql(type, options[:limit], options[:precision], options[:scale])})"
remove_column(table_name, column_name)
rename_column(table_name, tmp_column_name, column_name)
commit_db_transaction
rescue
rollback_db_transaction
end
end
change_column_default(table_name, column_name, options[:default]) if options_include_default?(options)
change_column_null(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
end