Branching factor

As explained in Just Use Postgres!

A branching factor is the average number of child entries or nodes associated with each branch in a tree structure.

A branching factor is the average number of entries stored in each branch node of a tree. In a B-tree index, it helps determine how quickly a search reaches the leaf containing a table reference. section 4.1

Estimating index lookups

For an index with 100 entries and branching factor 3, the search requires up to O(log₃100) = 4 index lookups. Each lookup visits one index node on the path from the root toward the matching leaf. section 4.1

Figure 4.1 A sample B-tree index showing the search path to the index entry with ID = 5

Trace the search path for ID = 5 through the root, branch nodes, and linked leaf nodes of a sample B-tree index. section 4.1

How Just Use Postgres! covers it

How deep it goes

Defines branching factor and works through logarithmic lookup cost, without developing deeper tree mathematics.

Examples

Uses a B-tree search for ID = 5 and calculates four lookups for 100 entries with branching factor three.

What it assumes

Assumes familiarity with tree nodes and database indexes while defining branching factor directly.

What you can do after

Evaluate approximate B-tree index lookup counts from entry totals and branching factor.

How it connects

Connects branching factor with B-tree indexes, logarithmic complexity, leaf nodes, range queries, and ordered data retrieval.

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Also explained in

• 

  liveBookmanning.com
  Advanced Algorithms and Data StructuresA branching factor is the number of child branches or children assigned to each node in a tree-based data structure.
• 

  liveBookmanning.com
  Data-Oriented Programming: Reduce software complexityA branching factor is the number of child nodes or partitions produced at each level of a tree-structured data representation.
• 

  liveBookmanning.com
  Optimization Algorithms: AI techniques for design, planning, and control problemsThe number of successor states available from a node, commonly represented by the maximum or average number of children.

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Related concepts

• heapconfigures · A binary heap is an almost complete binary tree in which each parent satisfies an ordering property relative to its children, enabling efficient access to a minimum or maximum element.
• tree heightconfigures · Tree height is the number of edges on the longest downward path from a tree’s root to any node, typically a leaf.
• persistent listconfigured by · A persistent list is an immutable ordered list whose updates produce new versions while preserving earlier versions, typically through structural sharing.
• d-ary heapconfigures · A d-ary heap is a heap-ordered tree in which each internal node has at most a fixed number d greater than one of children.
• updateconfigures · Update is a heap operation that changes the priority of one or more stored elements and restores the heap ordering.
• deletionconfigures · Deletion is an operation that removes an item, association, or resource from a collection or system, or requests or marks it for removal.

This explainer was generated by Manning's knowledge graph from the text of Just Use Postgres!. The section links point to the parts of the book it draws on.