Semantic Search
Search that uses meaning instead of literal keyword matching, based on embeddings and semantic representations.
Classification
- ComplexityMedium
- Impact areaTechnical
- Decision typeArchitectural
- Organizational maturityIntermediate
Technical context
Principles & goals
Use cases & scenarios
Compromises
- Bias or hallucinations from pretrained models
- Privacy issues when handling sensitive content
- Cost escalation from large vector indexes and model inference
- Hybrid approach: use keyword filtering before vector retrieval.
- Regular re-embedding pipelines for stale documents
- Automated evaluation framework with user feedback
I/O & resources
- Source corpus (documents, product data, logs)
- Metadata and taxonomies
- Embedding models or pipeline
- Ranked hit lists with scores and sources
- Explanations or highlighted passages
- Monitoring metrics and user feedback
Description
Semantic search augments keyword matching with semantic representations (embeddings) and retrieves content by meaning rather than literal terms. It leverages vector similarity, knowledge graphs and ranking signals to improve relevance for documents, chatbots and product search. Successful adoption requires data preparation, model choice and evaluation metrics.
✔Benefits
- Improved relevance via meaning-based matching
- Better handling of synonyms and language variants
- Flexible use across document types
✖Limitations
- Requires explainable ranking signals for auditability
- Higher storage and indexing overhead (vectors)
- Dependency on embedding quality and domain adaptation
Trade-offs
Metrics
- Mean Reciprocal Rank (MRR)
Measures how high relevant hits appear in the ranking.
- Recall@K
Share of relevant documents in the top-K results.
- P95 latency
95th percentile of response time under production load.
Examples & implementations
Enterprise knowledge base with embeddings
Internal docs were embedded and exposed via a vector index; support cases are resolved faster.
E‑commerce semantic ranking
Product descriptions and user queries are semantically mapped, improving search results and conversion rates.
Chatbot with passage retrieval
Contextual passage retrieval yields more precise source citations in a knowledge chatbot's answers.
Implementation steps
Requirements analysis: define relevance criteria and SLOs.
Data preparation: clean corpus and enrich metadata.
Model selection: evaluate and fine-tune embedding models.
Indexing: generate vectors and load into index.
Testing & rollout: A/B tests, monitoring and incremental rollout.
⚠️ Technical debt & bottlenecks
Technical debt
- Unversioned embedding pipelines hinder reproducibility.
- Missing monitoring for index drift leads to quality degradation.
- Ad-hoc fallback rules increase long-term maintenance cost.
Known bottlenecks
Misuse examples
- Using generic embeddings without domain adaptation leads to poor matches.
- Ignoring privacy rules when indexing sensitive content.
- Relying solely on vector scores without fallbacks for OOV queries.
Typical traps
- Lack of evaluation data skews perception of relevance.
- Over-optimizing for benchmarks instead of product-relevant metrics.
- Underestimating inference and storage cost requirements.
Required skills
Architectural drivers
Constraints
- • Compute and storage budget for indexes and models
- • Privacy and compliance requirements
- • Latency SLOs for interactive applications