Basics

elastic search에서 무엇을 검색한 경우, 유사한 것들에 대해 검색 결과를 반환합니다.

Precision

image from https://youtu.be/CCTgroOcyfM?t=494

What portion of the retrieved data is actually relevant to the search query?

Recall

image from https://youtu.be/CCTgroOcyfM?t=518

What portion of relevant data is being returned as search results?

Precision and Recall are inversely related. like:

• Precision

  • query와 완벽히 매치되는 결과를 반환.

  • 반환되는 document가 적을 수 있음.

• Recall

  • retrieve lot of result

  • 많은 결과를 반환.

  • query에 대해 완벽히 매치되는 document가 아닐 수 있음.

Score

• value that represents how relevant a document is to that specific query

• score is computed for each document that is a hit.

• score use 2 type of data.

  • term frequency

  • inverse document frequency

TF (Term Frequency)

for example, let's say search term is "How to form good habits"

https://youtu.be/CCTgroOcyfM?t=830

IDF (Inverse Document Frequency)

IDF decrease weight which occur very frequently. our case, habit occurred very frequently.

https://youtu.be/CCTgroOcyfM?t=830

References

• https://esbook.kimjmin.net/05-search/5.3-relevancy