hash index

基本解釋

This article uses a rather basic hash index as an example.
本文使用一個非?；镜?hash 索引作為例子。
Forest of Trees indexes combine the advantages of a hash index with those of a traditional B+tree index when the first column of the index is not very selective.
如果索引的第一行不是有選擇性的，F(xiàn)orest of Trees 索引結合一個 hash 索引和傳統(tǒng) B+tree 索引的優(yōu)勢。
As before with the hash index, you need to define a key generator UDF, a range producer UDF, the index extension, and finally a UDF that exploits the index extension if possible.
與 hash 索引一樣，這里需要定義一個鍵生成器 UDF、一個范圍生成器 UDF、一個索引擴展以及一個利用索引擴展的 UDF。