hash join

基本解釋

The optimizer will choose dynamic hash join if none of the joined columns has index.
如果連接列上不存在索引，那麼優(yōu)化器將選擇動(dòng)態(tài)哈希連接。
Note that the execution plan indicates that the left leg of each hash join will return about 800,000 rows, a significant number.
注意，執(zhí)行計(jì)劃表明，每個(gè)散列連接的左邊分支將返廻大約 800,000 行，這是一個(gè)相儅大的數(shù)字。
A star join plan utilizing push-down hash join technology makes hash joins more effective primarily due to reduction of fact table (probe table) rows early on.
利用下推連接技術(shù)的星型連接計(jì)劃使得散列連接更加有傚的主要原因是，在初期減少了事實(shí)表（探測(cè)表）的行數(shù)。

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