chdb-sql
Use when the user wants to run SQL — especially analytical SQL — on local files (parquet/csv/json), URLs, S3 paths, or remote databases (Postgres, MySQL, MongoDB, ClickHouse Cloud, Iceberg, Delta Lake) without setting up a server. Provides chDB — embedded ClickHouse SQL in Python with 1000+ functions, Session for stateful multi-step pipelines, parametrized queries, and cross-source joins via s3(), mysql(), postgresql(), iceberg(), deltaLake(), remoteSecure() table functions. TRIGGER when: user wants SQL on parquet/csv/files or across remote analytical sources; uses ClickHouse SQL features (window functions, windowFunnel, geoToH3, JSON path ops, Session, parametrized queries); imports chdb or calls chdb.query(). SKIP this skill for pandas-style DataFrame method-chaining (use chdb-datastore instead) or ClickHouse server administration.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/clickhouse/agent-skills --skill chdb-sql- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads chdb-sql automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
Security audits
Independent scans of the skill's instructions and bundled files.
SKILL.md
The instructions your agent reads when the skill is triggered.
chdb SQL — ClickHouse in Your Python Process
Run ClickHouse SQL directly in Python — no server needed. Query local files, remote databases, and cloud storage with full ClickHouse SQL power.
pip install chdb
Decision Tree: Pick the Right API
1. One-off query on files or databases → chdb.query()
2. Multi-step analysis with tables → Session
3. DB-API 2.0 connection → chdb.connect()
4. Pandas-style DataFrame operations → Use chdb-datastore skill instead
chdb.query() — One Line, Any Data
import chdb
chdb.query("SELECT * FROM file('data.parquet', Parquet) WHERE price > 100 LIMIT 10") # local files
chdb.query("SELECT * FROM mysql('db:3306', 'shop', 'orders', 'root', 'pass')") # databases
chdb.query("SELECT * FROM s3('s3://bucket/data.parquet', NOSIGN) LIMIT 10") # cloud storage
chdb.query("SELECT * FROM deltaLake('s3://bucket/delta/table', NOSIGN) LIMIT 10") # data lakes
# Cross-source join
chdb.query("""
SELECT u.name, o.amount FROM mysql('db:3306', 'crm', 'users', 'root', 'pass') AS u
JOIN file('orders.parquet', Parquet) AS o ON u.id = o.user_id ORDER BY o.amount DESC
""")
data = {"name": ["Alice", "Bob"], "score": [95, 87]}
chdb.query("SELECT * FROM Python(data) ORDER BY score DESC") # Python data
df = chdb.query("SELECT * FROM numbers(10)", "DataFrame") # output formats
chdb.query("SELECT toDate({d:String}) + number FROM numbers({n:UInt64})",
"DataFrame", params={"d": "2025-01-01", "n": 30}) # parametrized
Table functions → table-functions.md | SQL functions → sql-functions.md | Full API → api-reference.md
Session — Stateful Analysis Pipelines
from chdb import session as chs
sess = chs.Session("./analytics_db") # persistent; Session() for in-memory
sess.query("CREATE TABLE users ENGINE=MergeTree() ORDER BY id AS SELECT * FROM mysql('db:3306','crm','users','root','pass')")
sess.query("CREATE TABLE events ENGINE=MergeTree() ORDER BY (ts,user_id) AS SELECT * FROM s3('s3://logs/events/*.parquet',NOSIGN)")
sess.query("""
SELECT u.country, count() AS cnt, uniqExact(e.user_id) AS users
FROM events e JOIN users u ON e.user_id = u.id
WHERE e.ts >= today() - 7 GROUP BY u.country ORDER BY cnt DESC
""", "Pretty").show()
sess.close()
Connection API (DB-API 2.0)
from chdb import dbapi
conn = dbapi.connect()
cur = conn.cursor()
cur.execute("SELECT * FROM file('data.parquet', Parquet) WHERE value > 100")
print(cur.fetchall())
cur.close()
conn.close()
Troubleshooting
| Problem | Fix |
|---|---|
ImportError: No module named 'chdb' | pip install chdb |
DB::Exception: FILE_NOT_FOUND | Check file path; use absolute path or verify cwd |
DB::Exception: Unknown table function | Check function name spelling (e.g., deltaLake not deltalake) |
| Connection refused to remote DB | Check host:port format; ensure remote DB allows connections |
| Environment check | Run python scripts/verify_install.py (from skill directory) |
References
- API Reference — query/Session/connect signatures
- Table Functions — All ClickHouse table functions
- SQL Functions — Commonly used SQL functions
- Examples — 9 runnable examples with expected output
- Official Docs
Note: This skill teaches how to use chdb SQL. For pandas-style operations, use the
chdb-datastoreskill. For contributing to chdb source code, see CLAUDE.md in the project root.
FAQ
What does the chdb-sql skill do?
Use when the user wants to run SQL — especially analytical SQL — on local files (parquet/csv/json), URLs, S3 paths, or remote databases (Postgres, MySQL, MongoDB, ClickHouse Cloud, Iceberg, Delta Lake) without setting up a server. Provides chDB — embedded ClickHouse SQL in Python with 1000+ functions, Session for stateful multi-step pipelines, parametrized queries, and cross-source joins via s3(), mysql(), postgresql(), iceberg(), deltaLake(), remoteSecure() table functions. TRIGGER when: user wants SQL on parquet/csv/files or across remote analytical sources; uses ClickHouse SQL features (window functions, windowFunnel, geoToH3, JSON path ops, Session, parametrized queries); imports chdb or calls chdb.query(). SKIP this skill for pandas-style DataFrame method-chaining (use chdb-datastore instead) or ClickHouse server administration.
How do I install chdb-sql?
Run npx skills add https://github.com/clickhouse/agent-skills --skill chdb-sql in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/chdb-sql/ (personal) or .claude/skills/chdb-sql/ (project).
Which AI agents can use chdb-sql?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is chdb-sql safe to install?
Security partners have reviewed it: Gen Agent Trust Hub passed; Socket passed; Snyk flagged items to review; ZeroLeaks passed. As with any skill, read the SKILL.md and bundled scripts before installing.
Who maintains chdb-sql?
It is published by clickhouse in clickhouse/agent-skills, and it is an official skill from the maker of the technology it covers. It has 8,956 recorded installs.
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