Five tree-structured representations of MongoDB

Five tree-structured representations of MongoDB

First type: Parent link structure

Db. categories. Insert ({_ID: "MongoDB", Parent:"Databases"})Db. categories. Insert ({_ID: "DBM", Parent:"Databases"})Db. categories. Insert ({_ID: "Databases", Parent:"Programming"})Db.categories.insert ({ _id:  Languages ", Parent: " Programming "}) db.insert ({_id: " Programming ", Parent:  "Books"}) db.categories.insert ( {_id: Span class= "hljs-string" > "Books", Parent:null})          

Characteristics:

1. Quick Get parent node:

   Db.categories.findOne ({_id: "MongoDB"}). Parent

2. Easy to create parent node index

   Db.categories.ensureIndex ({parent:1})

3. Get son node by querying parent node

   Db.categories.find ({parent: "Databases"})

4. Multiple queries are required to retrieve subtrees.

Second Type: sub-link structure

Db. categories. Insert ({_ID: "MongoDB", Children: []})Db. categories. Insert ({_ID: "DBM", Children: []})Db. categories. Insert ({_ID: "Databases", Children: ["MongoDB","dbm"]})Db. categories. Insert ({ _id: "Languages", Children: []})db. Categories. Insert ( { _id: " Programming ", Children: [ " Databases ", " Languages "]})db. Categories. Insert ( { _id:  "Books", Children: [ "Programming"]})          

Characteristics:

1. Quick Get son node

   Db.categories.findOne ({_id: "Databases"}). Children

2. Easy to create child node index

   Db.categories.ensureIndex ({children:1})

3. Get parent node by querying son node

   Db.categories.find ({children: "MongoDB"})

4. Suitable for storing storage graphs, one node may have multiple parents.

The third type: ancestor queue structure

Db. categories. Insert ({_ID: "MongoDB", Ancestors: ["Books","Programming","Databases"], Parent:"Databases"})Db. categories. Insert ({_ID: "dbm", Ancestors: ["Books","Programming","Databases"], Parent:"Databases"})Db. categories. Insert ({_ID: "Databases", Ancestors: ["Books","Programming"], Parent:"Programming"})Db. categories. Insert ({_ID:  "Languages", Ancestors: [ "Books", Span class= "hljs-string" > "programming"], Parent:  "Programming"})  Db.categories.insert ({_id: " Programming ", Ancestors: [ "Books"], Parent:  "Books"}) db.categories.insert ( {_id: Span class= "hljs-string" > "Books", Ancestors: [], parent:null})       / span>               

Characteristics:

1. Get Ancestors Fast

   Db.categories.findOne ({_id: "MongoDB"}). Ancestors

2. Easy to create ancestor node index

   Db.categories.ensureIndex ({ancestors:1})

3. retrieving descendants by querying ancestors

   Db.categories.find ({ancestors: "Programming"})

4. Ancestor mode is slightly slower than materialized path mode

Fourth type: materialized path structure

Db. categories. Insert ({_ID: "Books", Path:null})Db. categories. Insert ({_ID: "Programming", Path:", Books,"})Db. categories. Insert ({_ID: "Databases", Path:", Books,programming,"})Db. categories. Insert ({_id: Span class= "hljs-string" > "Languages", Path: db.categories.insert ( {_id: Span class= "hljs-string" > "MongoDB", Path: db.categories.insert ({ Span class= "Hljs-rule" >_id:  dbm ", Path: ", Books,programming,databases, "})        

Characteristics:

1. Retrieving sorting by query

   Db.categories.find (). Sort ({path:1})

2. Quick Find child nodes

   Db.categories.find ({path:/^,books,/}) Db.categories.find ({path:/^,books,/})

3. To create an index for a path

   Db.categories.ensureIndex ({path:1})

Fifth: Set model

Db. categories. Insert ({_ID: "Books", Parent:0, Left:1, right:12})Db. categories. Insert ({_ID: "Programming", Parent:"Books", left:2, right:11})Db. categories. Insert ({_ID: "Languages", Parent:"Programming", left:3, right:4})Db. categories. Insert ({_ID: "Databases", Parent:"Programming", left:5, right: 10}) db. Categories. Insert ( { _id: "MongoDB", Parent: "Databases", left: 6, right: 7})db. Categories. Insert ( { _id: "dbm", Parent: "Databases", left: 8 , right: 9})                

Characteristics:

1. Quickly get child nodes

   var databasecategory = Db.categories.findOne ({_id: "Databases"}); Db.categories.find ({left: {$gt: Databasecategory.left}, right: {$lt: Databasecategory.right}});

2. Content modification is inefficient for static trees.

Five tree-structured representations of MongoDB