Neo4j 如何在内部存储数据? [英] How Neo4j stores data internally?

问题描述

我的问题是从开发者的角度出发的(不是专门针对用户)，可能有点乱.我想知道节点和关系的结构如何在逻辑上存储在数据库中.就像，当我说我有 bla bla 信息时.在哪里?- 那么答案是，在 BOOK 中，要么以 Grid 形式要么以页面上的线条形式.在 RDBMS 的情况下，数据以网格/表格格式存储.但我无法理解图形是如何存储在 Neo4j/图形数据库中的.我使用的是 Neo4j 客户端 2.1.2.

My question is from the view of developer (not specifically respect to User) and may be bit messy. I want to know that how the structure of Nodes and Relationships is get stored in database logically. Like, when I say that I have bla bla information. Where? - then the answer is, in BOOK, either in form of Grid or lines on a page. In case of RDBMS, data is stored in Grid/Tabular format. But I am unable to understand how graph is get stored in Neo4j/graph database. I am using neo4j client 2.1.2.

推荐答案

http://www.slideshare.net/thobe/an-overview-of-neo4j-internals 已经很过时了，但这让您对 Neo4j 的逻辑表示有了一个很好的概述.

http://www.slideshare.net/thobe/an-overview-of-neo4j-internals is very outdated but this gives you a good overview of Neo4j logical representation.

节点引用:

• 它的第一个标签(我的猜测是标签存储为单向链表)
• 它的第一个属性(属性被组织成一个单向链表)
• 它的开始/结束关系

关系被组织成双向链表.关系指向:

Relationships are organized as doubly linked lists. A relationship points to:

• 它的第一个属性(与节点相同)
• 其起始节点的前驱和后继关系
• 其端节点的前驱和后继关系

由于这种链式结构，遍历的概念(即查询数据的方式)很容易出现.这就是像 Neo4j 这样的图数据库擅长遍历图结构数据的原因.

Because of this chaining structure, the notion of traversal (i.e. THE way of querying data) easily emerges. That's why a graph database like Neo4j excels at traversing graph-structured data.

我粗略的猜测也是，因为 Neo4j 2.1 版(和 其新引入的密集节点管理)，节点的关系按类型隔离.通过这样做，如果一个节点 N 例如是 5 个类型 A 关系和 500 万个类型 B 关系的起始节点，则遍历类型 A 的 N 关系仍然是 O(n=5).

My rough guess would be also, since Neo4j version 2.1 (and its newly introduced dense node management), nodes' relationships are segregated by type. By doing so, if a node N is for example a start node for 5 relationships of type A and for 5 million rels of type B, traversing rels of type A for N remains O(n=5).

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