How to Connect ClickHouse to Codex
Query your ClickHouse data directly from Codex using Sequel’s MCP server. Ask questions in plain English, with no SQL, no dashboards, and no context switching.
Short answer
Connect ClickHouse to Sequel, then add Sequel's MCP server to Codex using the config on this page. Codex can then query your live ClickHouse data in plain English, with no connector code and no CSV exports. Both steps take a few minutes.
Everything you can ask Codex about your ClickHouse data.
Ask in plain English — Sequel translates it into a ClickHouse query, runs it, and Codex hands back the answer. No SQL, no dashboards, no CSV exports.
- How many events did we receive per hour yesterday?
- What's the funnel conversion rate from signup to first purchase?
- Show me the top 10 users by event count this week
- Which event types have increased most in the last 7 days?
- What's the day-1 retention rate for users who signed up last month?
How it works
Three steps to get started
Connect ClickHouse to Sequel
In your Sequel dashboard, go to Connections and add ClickHouse. Sequel handles authentication and schema discovery automatically.
Add Sequel to the agent
Copy the Sequel MCP configuration into Codex's settings file (shown below). Swap in your API key from Settings → API Keys.
Ask Codex about your data
Restart Codex and start asking questions. "How many events did we receive per hour yesterday?" — and get a real answer backed by live ClickHouse data.
Why Codex
What Codex does with your ClickHouse data
Grounded answers from real data
Codex with Sequel queries your actual databases before generating code or explanations. Every schema reference, column name, and data shape is verified against what's really there.
Terminal-native data access
No context switching — Codex can pull database data mid-session to inform code generation, write migrations based on actual schemas, and validate assumptions without leaving the terminal.
Agentic data workflows
Codex's multi-step agent can chain Sequel tool calls together: discover schema, sample data, run analysis, then generate code — all in one automated flow.
Configuration
Add Sequel to Codex
Place this in ~/.codex/config.yaml and replace sql_your_api_key with a key from Settings → API Keys.
~/.codex/config.yaml
mcp_servers:
sequel:
type: http
url: https://api.sequel.sh/mcp
headers:
Authorization: "Bearer sql_your_api_key"Install
Install ClickHouse MCP in Codex
Pick your app and Sequel installs itself: a one-click link where the client supports it, that client’s own few steps where it doesn’t. Every route signs in with your Sequel account over OAuth, so there is no API key to copy and nothing to keep in sync.
Already have an MCP client?
https://api.sequel.sh/mcp
Add it as a remote (streamable HTTP) server and sign in when prompted. Skills come with it; nothing else to install. Manual setup per client
Add Sequel to Codex
Terminal
codex mcp add sequel --url https://api.sequel.sh/mcp
- 1Run the command in your terminal. It writes the server to ~/.codex/config.toml.
- 2Run codex mcp login sequel and sign in in the browser.
- 3Start Codex and ask a question.
Other AI agents
Connect ClickHouse MCP to any agent
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Windsurf
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Zed
Connect Zed's AI assistant to your databases for real-time data access while you code.
Gemini
Connect Google Gemini to your databases for grounded, data-backed answers.
Claude Code
Query your databases directly from the Claude Code CLI — without leaving your terminal.
Codex
Give OpenAI Codex CLI real-time database access for data-grounded coding sessions.
OpenClaw
Turn your self-hosted OpenClaw agent into a data analyst that queries every source you've connected.
Hermes
Give Nous Research's Hermes agent read access to every database and marketing tool you've connected.
Grok Bot
Tell your Grok bot to add Sequel and it can query every database and marketing tool you've connected.
Muse
Give Meta's Muse one message and it builds its own connector to every source you've put in Sequel.
dots
Add Sequel once in ChatGPT and your dot can answer data questions on its own, day and night.
Other data sources
Connect other sources to Codex
PostgreSQL
Query your PostgreSQL database in plain English. No SQL required.
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Instant insights from your MySQL database. Ask in plain English.
BigQuery
Query petabytes of BigQuery data in plain English.
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Ask your GA4 data anything. No SQL, no dashboards.
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Unlock your SEO data with natural language. No exports, no pivot tables.
MCP Server
Connect any MCP-compatible server and query it with AI in seconds.
Stripe
Ask your Stripe data anything. MRR, churn, refunds — answered in plain English.
Polar
Ask your Polar revenue, subscriptions, and usage data anything — in plain English.
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PostHog
Ask your PostHog product data anything — with HogQL under the hood.
Mixpanel
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Amplitude
Query your Amplitude taxonomy, funnels, and dashboards in plain English.
HubSpot
Your AI analyst for HubSpot contacts, deals, tickets, and pipelines.
Ahrefs
Ask your Ahrefs SEO data anything: backlinks, keywords, and traffic.
Apollo.io
Ask your Apollo.io prospects, contacts, and accounts anything, in plain English.
Cloudflare D1
Ask your Cloudflare D1 database questions in plain English.
Instagram organic analytics — post engagement, reach, and audience insights in plain English.
Frequently asked questions
How do I connect ClickHouse to Codex?
You need two things: (1) connect ClickHouse to Sequel in your Sequel dashboard under Connections, and (2) add the Sequel MCP config to Codex using the setup shown above. Once both are done, Codex can query your ClickHouse data directly.
What ClickHouse data can Codex access?
Codex can access any data available through your ClickHouse connection in Sequel. Use Sequel's search tool to discover available metrics and dimensions, then execute queries to pull the data you need.
Is my ClickHouse data sent to Codex's servers?
Query results are returned to Codex as context within your conversation. Only the data you explicitly ask about is retrieved. Sequel never stores your query results permanently — they exist only for the duration of the tool call.
Do I need a Sequel account?
Yes. You need a Sequel account to connect ClickHouse and generate an API key. Sign up free at sequel.sh — no credit card required. Then create a connection to ClickHouse and generate an API key from Settings → API Keys.
Can I connect multiple ClickHouse accounts?
Yes. Sequel supports multiple connections of the same type. If you have multiple ClickHouse accounts or properties, add each as a separate connection in Sequel. Codex will be able to query all of them.
How do I configure Sequel for Codex CLI?
Add the Sequel MCP server to ~/.codex/config.yaml as shown above. Create the file if it doesn't exist. Replace `sql_your_api_key` with a real key from Settings → API Keys, then restart Codex.
Does Codex CLI support HTTP MCP servers?
Yes. Codex CLI supports MCP over HTTP (Streamable HTTP transport). The `type: http` field in the config tells Codex to use this transport when connecting to Sequel.
Can I limit which databases Codex can access?
Sequel MCP is scoped to your organization's connected data sources. You can create separate API keys for different environments and revoke them at any time from Settings → API Keys.
Is this the same as the original OpenAI Codex model?
No — Codex CLI is OpenAI's agentic terminal coding tool, separate from the original Codex language model. It uses the latest OpenAI models (GPT-4o and o-series) with MCP tool support.
How do I connect ClickHouse?
Click 'New Connection', select ClickHouse, and enter your host, port, database, username, and password. Sequel supports both HTTP and native interfaces.
Which ClickHouse versions are supported?
Sequel supports ClickHouse 21.x and above, including ClickHouse Cloud.
Can Sequel handle large ClickHouse tables?
Yes. Sequel adds LIMIT clauses by default and warns you before running queries that may trigger full table scans on large datasets. ClickHouse's columnar storage makes even large queries fast.
Does Sequel use ClickHouse-specific SQL features?
Yes. Sequel generates ClickHouse-compatible SQL including toStartOfHour, toDate, arrayJoin, and other ClickHouse functions when appropriate.
Connect ClickHouse to Codex today
Sign up free, connect your data sources, and start querying in minutes.