[Feature]: Replace naive regex-based question search with MongoDB full-text index for relevance-ranked results

[prince-pokharna]

enhancement, feature, backend, performance, GSSoC 2026

Summary

StackIt's current search implementation (GET /api/questions with a keyword param) almost certainly uses $regex against question titles. This performs a full collection scan on every search — O(n) complexity — with no relevance ranking and no support for partial word matching or tag-based boosting. For a Q&A platform aspiring to be a professional Stack Overflow alternative, relevance-ranked full-text search is a baseline expectation.

Problem

• $regex performs a full collection scan (no index used), degrading linearly as question count grows.
• No relevance ranking — results are returned in insertion order, not by semantic match quality.
• No stemming, stop-word filtering, or phrase-match support.
• Search does not cover answer bodies or tags — only question titles.
• No search analytics or autocomplete suggestions.

Impact

• As the question count grows beyond a few thousand, search becomes unusably slow.
• Poor relevance ordering means users cannot find the answers they need, undermining the platform's core value.

Proposed Solution

1. Add MongoDB text indexes on the questions collection:

// server/models/Question.js — add index
QuestionSchema.index(
  { title: 'text', body: 'text', tags: 'text' },
  {
    weights: { title: 10, tags: 5, body: 1 },
    name: 'question_full_text_index'
  }
);

2. Update the search controller to use $text with score-based sorting:

// server/routes/questions.js
if (keyword) {
  const results = await Question.find(
    { $text: { $search: keyword } },
    { score: { $meta: 'textScore' } }
  )
  .sort({ score: { $meta: 'textScore' } })
  .populate('author', 'username reputation')
  .lean();

  return res.json(results);
}

3. Add a migration script that builds the text index on the existing collection without downtime using createIndex with background: true.

4. Add tag-based autocomplete endpoint (GET /api/search/suggestions?q=<prefix>) for the search bar.

I am participating in GSSoC 2026. Could you please assign this issue to me?

[prince-pokharna]

Hey @Ashmita1206 ,
Please assign it to me under GSSoC 2026.
/assign /claim /claim-assignment