{
  "id": "add-postgres-full-text-search",
  "type": "prompts",
  "category": "prompts",
  "locale": "en",
  "url": "/prompts/add-postgres-full-text-search",
  "title": "Prompt to Add PostgreSQL Full-Text Search",
  "description": "Copy-paste AI prompt to add native PostgreSQL full-text search with tsvector, GIN index, and ranked results to an existing Next.js app.",
  "tools": [
    "Cursor",
    "Claude Code",
    "Codex",
    "Windsurf"
  ],
  "stack": [
    "Next.js",
    "PostgreSQL",
    "TypeScript"
  ],
  "tags": [
    "postgres",
    "sql",
    "search",
    "nextjs",
    "typescript"
  ],
  "difficulty": "medium",
  "updated": "2026-06-08",
  "markdown": "Use this prompt to add real PostgreSQL full-text search to an existing app — using\n`tsvector`, a GIN index, and `ts_rank` — without the agent reaching for Elasticsearch,\nAlgolia, or a third-party search API.\n\n## Main Prompt\n\n```txt title=\"Main Prompt\"\nYou are working in a Next.js App Router project with TypeScript and PostgreSQL (using the\n`postgres` npm package, not Prisma or Drizzle).\n\nTask: add full-text search over the `posts` table (columns: id, title, body, created_at).\n\nDatabase changes:\n1. Write a migration file `migrations/0010_add_fts.sql` that:\n   - Adds a generated column: `search_vector tsvector GENERATED ALWAYS AS\n     (to_tsvector('english', coalesce(title,'') || ' ' || coalesce(body,''))) STORED;`\n   - Creates a GIN index: `CREATE INDEX posts_search_idx ON posts USING GIN (search_vector);`\n2. Do NOT use `pg_trgm` or LIKE queries — use `@@` with `to_tsquery` or `websearch_to_tsquery`.\n\nApplication changes:\n- Create `src/lib/search.ts` with a `searchPosts(query: string, limit = 20)` function that:\n  - Uses `websearch_to_tsquery('english', $1)` to parse the query safely.\n  - Returns rows ordered by `ts_rank(search_vector, query_vector) DESC`.\n  - Returns `{ id, title, body_excerpt, rank }` — body_excerpt via `ts_headline`.\n  - Uses parameterized queries only — no string interpolation.\n- Create a Server Action `src/lib/actions/search.ts` that calls `searchPosts` and returns results.\n- Create `src/components/SearchBox.tsx` (Client Component) with a debounced input (300 ms) that\n  calls the Server Action via `useTransition` and renders results.\n\nDo not install pg_search, Meilisearch, or any search service. Stop and list files before coding.\n```\n\n## Implementation Notes\n\n- `websearch_to_tsquery` is safer than `to_tsquery` for user input because it tolerates malformed\n  queries (missing operators, special characters) without throwing a PostgreSQL error.\n- The generated `tsvector` column is automatically updated on INSERT/UPDATE — no triggers needed.\n- `ts_headline` requires the original column text and the query vector; pass both from the SELECT.\n- The GIN index makes search fast on large tables; without it queries will sequential-scan.\n\n## Expected File Changes\n\n```txt\nmigrations/0010_add_fts.sql              (new)\nsrc/lib/search.ts                        (new)\nsrc/lib/actions/search.ts               (new — Server Action)\nsrc/components/SearchBox.tsx            (new — Client Component)\n```\n\n## Acceptance Criteria\n\n- `psql -f migrations/0010_add_fts.sql` runs without error on the existing schema.\n- Searching for a word that appears only in `title` returns the correct post.\n- Searching for a phrase with a typo (e.g., \"postgress\") returns no results without crashing.\n- Results are ordered with higher-relevance posts first.\n\n## Test Commands\n\n```bash\npsql \"$DATABASE_URL\" -f migrations/0010_add_fts.sql\nbun run typecheck\nbun run dev\n# type a search term in SearchBox and verify ranked results appear\npsql \"$DATABASE_URL\" -c \"EXPLAIN ANALYZE SELECT * FROM posts WHERE search_vector @@ websearch_to_tsquery('english','test');\"\n# confirm \"Index Scan using posts_search_idx\" appears in output\n```\n\n## Common AI Mistakes\n\n- Using `LIKE '%query%'` instead of the `@@` full-text operator.\n- Using `to_tsquery('english', $1)` with raw user input — breaks on queries like `\"foo bar\"`.\n- Forgetting the GIN index, leaving the search as a sequential scan.\n- Calling `searchPosts` in a Client Component instead of wrapping it in a Server Action.\n\n## Fix Prompt\n\n```txt title=\"Fix Prompt\"\nThe search is using LIKE or crashing on special characters. Fix in order:\n1. Replace any LIKE clause with `search_vector @@ websearch_to_tsquery('english', $1)`.\n2. If `to_tsquery` is used directly with user input, replace it with `websearch_to_tsquery`.\n3. Confirm the GIN index exists: `CREATE INDEX IF NOT EXISTS posts_search_idx ON posts USING GIN (search_vector);`\nShow only the corrected diff. Do not modify unrelated files.\n```"
}