express

sumak + Express

Minimal Express 5 server: paginated streaming, transactional writes, AbortSignal-aware deletes.

Shape

• src/schema.ts — table definitions (users, posts)
• src/db.ts — single Pool + single sumak() instance, reused across requests
• src/server.ts — three routes exercising query, transaction, streaming, cancellation

Run

export DATABASE_URL="postgres://postgres:pg@localhost:5432/postgres"
pnpm install
pnpm migrate     # creates tables via `sumak migrate up`
pnpm dev

curl http://localhost:3000/posts?limit=100
curl -X POST http://localhost:3000/posts \
  -H 'content-type: application/json' \
  -d '{"authorEmail":"ada@x.io","title":"first","body":"hello"}'

Worth noting

• One sumak per process. Don't build a fresh sumak() per request — the connection pool is what you share, not the query builder. Per-request context (tenant id, audit userId) plugs in via db.withSchema(...) or plugin factories; the base instance stays immutable.
• Streaming NDJSON. db.selectFrom(...).stream() returns an AsyncIterable that backs onto pg's server-side cursor. For a 10M-row export you keep a handful of rows in memory at once.
• AbortSignal on DELETE. A client drop fires the close event on the request; we propagate that to the driver via { signal }, which cancels the query server-side rather than letting it complete against a dead socket.
• Transactions are RAII. db.transaction(async tx => ...) begins, passes tx to the callback, commits on return, rolls back on throw. The tx parameter is a bound sumak instance — it has the same API as db but with every statement issued on the same connection.