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Atlas Whoff
Atlas Whoff

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Implementing Search: From Basic SQL LIKE to Full-Text to Vector

Implementing Search: From Basic SQL LIKE to Full-Text to Vector

There's a search solution for every scale. Here's when to use each.

Level 1: SQL LIKE / ILIKE

Good enough for small datasets and prefix searches:

-- Prefix search (can use index)
SELECT * FROM products WHERE name ILIKE 'coffee%';

-- Substring search (sequential scan — slow at scale)
SELECT * FROM products WHERE name ILIKE '%coffee%';
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Works well under 10k rows. Above that, full-text search is better.

Level 2: PostgreSQL Full-Text Search

-- Add a tsvector column for fast searching
ALTER TABLE products ADD COLUMN search_vector tsvector;

-- Populate it
UPDATE products SET search_vector =
  to_tsvector('english', coalesce(name,'') || ' ' || coalesce(description,''));

-- Index it
CREATE INDEX idx_products_search ON products USING gin(search_vector);

-- Search with ranking
SELECT id, name,
  ts_rank(search_vector, query) AS rank
FROM products, to_tsquery('english', 'coffee & beans') query
WHERE search_vector @@ query
ORDER BY rank DESC
LIMIT 20;
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// Prisma raw query for full-text search
const results = await prisma.$queryRaw`
  SELECT id, name, ts_rank(search_vector, query) as rank
  FROM products, plainto_tsquery('english', ${searchTerm}) query
  WHERE search_vector @@ query
  ORDER BY rank DESC
  LIMIT 20
`;
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Level 3: Vector/Semantic Search

For 'find similar' or natural language search, embeddings beat keyword matching:

import Anthropic from '@anthropic-ai/sdk';

async function embedText(text: string): Promise<number[]> {
  const response = await anthropic.embeddings.create({
    model: 'voyage-3',
    input: text,
  });
  return response.data[0].embedding;
}

// Store in pgvector
await prisma.$executeRaw`
  INSERT INTO product_embeddings (product_id, embedding)
  VALUES (${productId}, ${embedding}::vector)
`;

// Search by similarity
const queryEmbedding = await embedText(userQuery);
const results = await prisma.$queryRaw`
  SELECT p.id, p.name,
    1 - (e.embedding <=> ${queryEmbedding}::vector) AS similarity
  FROM products p
  JOIN product_embeddings e ON e.product_id = p.id
  ORDER BY similarity DESC
  LIMIT 10
`;
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Which to Choose

Scale / Need Solution
< 10k rows, simple SQL LIKE
> 10k rows, keyword PostgreSQL FTS
Semantic / fuzzy Vector search
Complex relevance tuning Elasticsearch

Vector search is central to RAG pipelines and AI-powered features. For a deep dive on embeddings, RAG architecture, and pgvector setup, the AI SaaS Starter Kit includes a working search implementation.


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