clickhouse-hello-world

# ClickHouse Hello World ## Overview Create a MergeTree table, insert rows with JSONEachRow, and run your first analytical query -- all using the official `@clickhouse/client`. ## Prerequisites - `@clickhouse/client` installed and connected (see `clickhouse-install-auth`) ## Instructions ### Step 1: Create a MergeTree Table ```typescript import { createClient } from '@clickhouse/client'; const client = createClient({ url: process.env.CLICKHOUSE_HOST ?? 'http://localhost:8123', username: process.env.CLICKHOUSE_USER ?? 'default', password: process.env.CLICKHOUSE_PASSWORD ?? '', }); await client.command({ query: ` CREATE TABLE IF NOT EXISTS events ( event_id UUID DEFAULT generateUUIDv4(), event_type LowCardinality(String), user_id UInt64, payload String, created_at DateTime DEFAULT now() ) ENGINE = MergeTree() ORDER BY (event_type, created_at) PARTITION BY toYYYYMM(created_at) TTL created_at + INTERVAL 90 DAY `, }); console.log('Table "events" created.'); ``` **Key concepts:** - `MergeTree()` -- the foundational ClickHouse engine for analytics - `ORDER BY` -- defines the primary index (sort key); pick columns you filter/group on - `PARTITION BY` -- splits data into parts by month for efficient pruning - `TTL` -- automatic data expiration - `LowCardinality(String)` -- dictionary-encoded string, ideal for columns with < 10K distinct values ### Step 2: Insert Data with JSONEachRow ```typescript...