Amdahl's Law states that the performance improvement to be gained from using some faster modeofexecution is limited by the fraction of the time the faster mode can be used.
阿姆达定律表明：通过改进某模式得到的整体性能提高，受限于该改进模式所占的运行时间比例。
2
Use this mode to perform any maintenance task, including tasks requiring the executionof SQL and DDL statements, when no other users are connected to the database server.