@JohnKoepi @ g on software engineering

System design problem - w-shingles search engine

You are asked to develop a system that helps scientists to answer a question whether their papers contain non-unique content (are plagiarism). The system will index millions of documents and check whether a document from the input contains pieces from other (indexed) documents.


Develop a w-shingles search engine that exposes following API:

  • POST /index/add {doc_id: uint64, shingles: []uint64} - index a document
  • POST /index/search {shingles: []uint64} - search index for a ranked document ids

Where a document is a text that is translated into a sequence of shingles:

text:string → shingles:uint64[]

A search query returns a list of ranked documents ordered by the size of intersection of their its and the ones from the request set.


  • Search shingles set is up to 10^6 per query.
  • Index size: index contain about 10^9 documents (~10^12 shingles).
  • Search must handle at least 300*10^3 request per day.
  • Index filling must handle 4000 RPS.
  • All these constraints must be met with a single machine.
  • The system must be able to scale beyond the single machine.
blog comments powered by Disqus