说明：  超大型数据库的大小常常达到数百GB，有时甚至要用TB来计算。而单表的数据量往往会达到上亿的记录，并且记录数会随着时间而增长。这不但影响着数据库的运行效率，也增大数据库的维护难度。除了表的数据量外，对表不同的访问模式也可能会影响性能和可用性。这些问题都可以通过对大表进行合理分区得到很大的改善。当表和索引变得非常大时，分区可以将数据分为更小、更容易管理的部分来提高系统的运行效率。
(Large size of the database is often hundreds of GB, and sometimes even use the TB calculation. The single-table data often reach hundreds of millions of records, and records will increase with time. This not only affects the operating efficiency of the database, but also increases the difficulty of maintaining the database. In addition to the amount of data table, the table different access patterns may also affect the performance and availability. These problems can be a reasonable partitioning of large tables has been greatly improved. When the tables and indexes become very large, the data can be partitioned into smaller, more manageable parts to improve the efficiency of the system.)