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This page explains the composable tuning API for fine‑grained ranking and typo behavior. Use it to adjust prefix/infix mode, typo tolerances, and field weights.

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DSL usage

rel = SearchEngine::Book
  .ranking(num_typos: 1, drop_tokens_threshold: 0.2, prioritize_exact_match: true, query_by_weights: { title: 3, description: 1 })
  .prefix(:disabled) # or :fallback/:always depending on research
Additional variations: 
# Prefix only
SearchEngine::Book.prefix(:fallback)

# Weights aligned to a three‑field query_by
# With config.default_query_by = "title, description, author"
SearchEngine::Book
  .ranking(query_by_weights: { title: 3, description: 1 })

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Compiler mapping

  • ranking(num_typos:) → num_typos (0/1/2)
  • ranking(drop_tokens_threshold:) → drop_tokens_threshold (0.0..1.0)
  • ranking(prioritize_exact_match:) → prioritize_exact_match (Boolean)
  • ranking(query_by_weights:) → query_by_weights as a comma list aligned to the effective query_by fields; fields without explicit weight default to 1
  • prefix(mode) → infix where:
    • :disabled → "off"
    • :fallback → "fallback"
    • :always → "always"

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Explain & DX

  • rel.dry_run! includes the compiled params in { url:, body:, url_opts: }
  • rel.explain shows:
    • effective query_by fields
    • weight vector (defaults filled with 1)
    • num_typos, drop_tokens_threshold, prioritize_exact_match, prefix (via infix token)
See also: DX, Relation Guide, and Cookbook Queries.

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Guidance

  • Start with: num_typos=1, drop_tokens_threshold≈0.2, prefix=:fallback
  • Increase weights gradually; avoid setting all weights to 0
  • Prefer explicit query_by per search or configure SearchEngine.config.default_query_by

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Troubleshooting

  • Weight for unknown field:
  • Threshold out of range:
    • Use 0.0..1.0
  • All weights zero:
    • At least one field must have weight > 0
  • Unknown prefix mode:
    • Valid: :disabled, :fallback, :always