ClickHouse Node.js Client — Coding
Reference: https://clickhouse.com/docs/integrations/javascript
⚠️ Node.js runtime only. This skill covers the
@clickhouse/clientpackage 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.
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How to Use This Skill
- 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.
- 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.
- Prefer
JSONEachRowfor 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.
- Always use
query_paramsfor 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.
- 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.
- Note version constraints when relevant. Examples:
pathnameconfig option: client>= 1.0.0.BigIntvalues inquery_params: client>= 1.15.0.TupleParamand JSMapinquery_params: client>= 1.9.0.- Configurable
json.parse/json.stringify: client>= 1.14.0. Time/Time64data types: ClickHouse server>= 25.6.QBitdata type: ClickHouse server>= 25.10(GA on26.x).Dynamic/Variant/ newJSONtypes: ClickHouse server>= 24.1/
24.5 / 24.8 (no longer experimental since 25.3).
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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 | reference/insert-formats.md |
| Insert into a subset of columns / different database | insert({ columns }), excluding columns, ephemeral columns, cross-DB inserts | reference/insert-columns.md |
| Insert values, expressions, dates, decimals | INSERT … VALUES with SQL functions, Date/DateTime from JS, Decimal precision, INSERT … SELECT; inserting a UUID into a UInt128 column is tricky — use when the user is writing code that stores a UUID as UInt128 | reference/insert-values.md |
| Async inserts (server-side batching) | async_insert=1, fire-and-forget vs wait-for-ack | reference/async-insert.md |
| Select and parse results | JSONEachRow reads, JSON with metadata, picking a select format | reference/select-formats.md |
| Parameterize queries | Binding values, special characters / escaping, "SQL injection?", {name: Type} syntax | reference/query-parameters.md |
| Sessions & temporary tables | session_id, CREATE TEMPORARY TABLE, per-session SET commands | reference/sessions.md |
| Modern data types | Dynamic, Variant, JSON (object), Time, Time64, QBit (vector search) | reference/data-types.md |
| Custom JSON parse/stringify | Plug in JSONBig / safe-stable-stringify / a BigInt-aware serializer | reference/custom-json.md |
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Conventions used in answers
- Always show
import { createClient } from '@clickhouse/client'(Node, never
Web).
- Always
await client.close()at the end of self-contained snippets; in
long-running services, close on graceful shutdown.
- For inserts, prefer
format: 'JSONEachRow'andvalues: [...]unless the
user's scenario requires otherwise.
- For selects, prefer
await (await client.query({...})).json<RowType>()for
small / medium result sets; for bigger results suggest streaming.
- When showing parameter binding, use ClickHouse's native
{name: Type}
syntax — never $1, ?, or :name.
- For DDL inside a cluster or behind a load balancer, set
clickhouse_settings: { wait_end_of_query: 1 } on the command() call so the server only acknowledges after the change is applied. See https://clickhouse.com/docs/en/interfaces/http/#response-buffering.
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Out of scope
This skill covers day-to-day coding against @clickhouse/client (Node). The following topics are intentionally not covered here:
- **Errors, hangs, type mismatches, proxy pathname surprises, log silence,
socket hang-ups, ECONNRESET** → use the clickhouse-js-node-troubleshooting skill.
- **Streaming, Parquet, file streams, server-side bulk moves, progress
streaming, async-insert throughput tuning** — see examples/node/performance/.
- TLS, RBAC / read-only users, deeper SQL-injection guidance — see
- **
CREATE TABLEpatterns, deployment-shaped connection strings,
replication / sharding choices** — see examples/node/schema-and-deployments/.
- Browser, Web Worker, Next.js Edge, Cloudflare Workers — use
@clickhouse/client-web and see examples/web/.
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Still Stuck?
examples/node/coding/— the runnable corpus this skill is built on.- ClickHouse JS client docs
- ClickHouse supported formats
- ClickHouse data types
