Tag: Multidimensional Analysis

In a multidimensional application, a fact table always has a lot of dimension tables. As the following shows, the orders table has a series of dimension tables: The association between any of the dimension tables and the fact table is the JOIN defined in SQL. Technically, databases use the HASH JOIN algorithm to achieve the joins, implementing one at a time. N times of HASH JOIN are needed when there are N joins, and each intermediate result set will be retained for use in the next join. The computing process is complex and involves multiple traversals, markedly dragging down the