/clickhouse-js-node-coding

name: clickhouse-js-node-coding
description: >
  Write idiomatic application code with the ClickHouse Node.js client
  (`@clickhouse/client`). Use this skill whenever a user is *building* against
  the Node.js client — configuring the client, pinging, inserting rows in JSON
  or raw formats, selecting and parsing results, binding query parameters,
  managing sessions and temporary tables, working with data types or
  customizing JSON parsing. Do NOT use for browser/Web client code.

ClickHouse Node.js Client — Coding

Reference: https://clickhouse.com/docs/integrations/javascript

> **⚠️ Node.js runtime only.** This skill covers the `@clickhouse/client` > package running in a **Node.js runtime** exclusively — including **Next.js > Node runtime** API routes, React Server Components, Server Actions, and > standard Node.js processes. Do **not** apply this skill to browser client > components, Web Workers, **Next.js Edge runtime**, Cloudflare Workers, or > any usage of `@clickhouse/client-web`. For browser/edge environments, the > correct package is `@clickhouse/client-web`.

---

How to Use This Skill

1. **Match the user's intent** to a row in the Task Index below and read the corresponding reference file before writing code. After reading it, scan any **Answer checklist** in that reference and make sure the final answer covers each relevant item; those checklists capture details users usually need but are easy to omit in short answers. 2. **Always import from `@clickhouse/client`** (never `@clickhouse/client-web`) and create a client with `createClient({ url })` or rely on supported defaults when appropriate. Close it with `await client.close()` preferably when it's no longer needed or during graceful shutdown for global resources. 3. **Prefer `JSONEachRow` for typical row inserts/selects** unless the user has already chosen another format or is streaming raw bytes (CSV / TSV / Parquet — see `examples/node/performance/`). **Note on `clickhouse_settings`:** settings passed to `createClient` are defaults for every request; they can be overridden per-call by passing `clickhouse_settings` directly to `insert()`, `query()`, or `command()`. Always mention this when the user configures settings at the client level. 4. **Always use `query_params` for user-supplied values** — never template- literal-interpolate them into SQL. See `reference/query-parameters.md`. **When answering a parameter-binding question, your response must explicitly name template-literal interpolation as a "SQL injection risk"** — even when the user only asked about syntax and did not raise security. The literal phrase "SQL injection" needs to appear; this is the most common mistake from PostgreSQL/MySQL users and the security framing is part of the correct answer, not an optional aside. 5. **Pick the right method for the job:**

• `client.insert()` — write rows.
• `client.query()` + `resultSet.json()` / `.text()` / `.stream()` — read

rows that return data.

• `client.command()` — DDL and other statements that don't return rows

(`CREATE`, `DROP`, `TRUNCATE`, `ALTER`, `SET` in a session, etc.).

• `client.exec()` — when you need the raw response stream of an arbitrary

statement (rare in coding scenarios).

• `client.ping()` — health check; returns `{ success, error? }`, never

throws on connection failure. 6. **Note version constraints** when relevant. Examples:

• `pathname` config option: client `>= 1.0.0`.
• `BigInt` values in `query_params`: client `>= 1.15.0`.
• `TupleParam` and JS `Map` in `query_params`: client `>= 1.9.0`.
• Configurable `json.parse` / `json.stringify`: client `>= 1.14.0`.
• `Time` / `Time64` data types: ClickHouse server `>= 25.6`.
• `QBit` data type: ClickHouse server `>= 25.10` (GA on `26.x`).
• `Dynamic` / `Variant` / new `JSON` types: ClickHouse server `>= 24.1` /

`24.5` / `24.8` (no longer experimental since `25.3`).

---

Task Index

Identify the user's task and read the matching reference file.

| Task | Triggers / symptoms | Reference file | | -------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------- | | **Configure / connect the client** | Building a `createClient` call, URL parameters, `clickhouse_settings`, default format, custom HTTP headers | `reference/client-configuration.md` | | **Compress requests / responses** | `compression`, gzip vs `zstd`, `{ codec }` option shape, Node version requirements, web limitations | `reference/compression.md` | | **Ping the server** | Health checks, readiness probes, "is ClickHouse up?" | `reference/ping.md` | | **Choose an insert format** | "Which format should I use to insert?", JSON vs raw, `JSONEachRow` vs `JSON` vs `JSONObjectEachRow`