文件名称：查询命令的执行-Greenplum 数据库基础培训V1.2
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更新时间：2024-05-15 15:14:47
Greenplum 中文
查询命令的执行 举例说明：按卡号、客户号、机构的分布方式优劣点 分布存储 * Instructor Notes (animated slide) To understand how Greenplum Database stores data across the various hosts and segment instances, consider the following simple logical database schema. This shows a simple star schema common in data warehousing. In this type of database schema, the sale table is usually called a fact table and the other tables (customer, vendor, product) are usually called the dimension tables. Now let’s see what these tables look like in the physical database. (double-click) In Greenplum Database all tables are distributed, which means a table is divided into non-overlapping sets of rows or parts. Each part resides on a single database known as a segment within the Greenplum Database system. The parts are distributed evenly across all of the available segments using a sophisticated hashing algorithm. Distribution is determined at table create time by selecting a distribution key of one or more columns. Typically you would use a table’s primary key or some other unique column or set of columns as the distribution key.