Sharding是近几年提出的概念，可以做分表，分库切割，通过hash值定位。但都存在一个问题，数据连续性，索引无法跨表。
Oracle 在8.x中就支持分区功能，MySQL在5.1.x中也是闲类似功能，PostgreSQL 因存储结构设计的较好，基本不需要做分区。
ALTER TABLE `goods` DROP INDEX `goods_sn_2`;
ALTER TABLE goods PARTITION BY RANGE (goods_id) (
PARTITION p0 VALUES LESS THAN (10000),
PARTITION p1 VALUES LESS THAN (20000),
PARTITION p2 VALUES LESS THAN (30000),
PARTITION p3 VALUES LESS THAN (40000),
PARTITION p4 VALUES LESS THAN MAXVALUE
);
ALTER TABLE goods PARTITION BY HASH(goods_id) PARTITIONS 10;
ALTER TABLE goods PARTITION BY KEY (is_on_sale) PARTITIONS 2;
ALTER TABLE goods PARTITION BY HASH(YEAR(FROM_UNIXTIME(add_time))) PARTITIONS 4;