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Oracle 解释执行计划

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Release： 2016-06-07 17:26:13
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执行计划展示的时候类似于一个表格形式，其实它是一个树形结构。该树形结构不仅阐述了SQL引擎执行操作的顺序，也阐明了它们之间的

一. 执行计划树形结构

执行计划展示的时候类似于一个表格形式，其实它是一个树形结构。该树形结构不仅阐述了SQL引擎执行操作的顺序，也阐明了它们之间的关系。树上的每一个节点都代表一个操作，比如表访问，连接，，排序等。各操作之间存在父子关系，具体规则如下：

1. 父有一个或多个子

2. 子只有一个父

3. 唯一没有父的是根节点

4. 执行计划显示的时候，子缩进到父的右侧

5. 父在他孩子前面（父ID小于孩子的ID）

如下图所示：

对应树形结构

下面我们将分类解释各种执行计划

linux

Related labels：
Oracle解释计划 Oracle执行计划 Oracle 解
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