Introduction to elasticsearch

• Elasticsearch
• Structure
• Search Type
• Scoring

Elasticsearch

is a search engine based on Lucene. It provides a distributed, multitenant-capable full-text search engine with an HTTP web interface and schema-free JSON documents.

Structure

Relational DB-> Databases-> Tables->Rows -> Columns

Elasticsearch-> Indices  -> Types ->Documents -> Fields

Search Type

Structured search(term)
Full-text search(analysis)

Scoring

It uses Lucene’s Practical Scoring Function,combining the TF/IDF score with other factors such as the term proximity in phrase queries, or term similarity in fuzzy queries.

• Boolean Model tf(t in d) = √frequency
  
• Inverse document frequency idf(t) = 1 + log ( numDocs / (docFreq + 1))
  
• Field-length norm norm(d) = 1 / √numTerms
  
• Vector Space In the vector space model, each number in the vector is the weight of a term.
  

The End!
Reference: https://www.elastic.co/

Author

Typing Theme

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