# Expert incident response for ClickHouse

> Our founding team picks up your incident, and Polylane's agents dig through your logs, metrics, traces and code with them.

- **Real engineers who've carried the pager.** The team has been on-call at Cloudflare, Webflow, Groq, Twilio, and Robinhood. They've been where you are right now.
- **Multi-cloud incident response.** Polylane investigates incidents across AWS, Cloudflare, Vercel, Kubernetes and the rest of your stack, from the edge to the database.
- **Unified context & investigation.** Logs, metrics, traces, deploys and code in one context graph. Connect in minutes, not weeks.
- **Least-privilege access.** New cloud accounts connect read-only, with scoped credentials. Nothing in production changes unless you allow it.

## My ClickHouse database is failing. What should I do?

On ClickHouse Cloud, check [status.clickhouse.com](https://status.clickhouse.com/) first. Then read the error code: `MEMORY_LIMIT_EXCEEDED` (241) means a query needs more memory than allowed, `TOO_MANY_SIMULTANEOUS_QUERIES` (202) means you hit the concurrency limit, and `TOO_MANY_PARTS` (252) means inserts arrive in batches too small to merge. `system.query_log` and `system.errors` show what fails.

1. **Check ClickHouse Cloud's status.** [status.clickhouse.com](https://status.clickhouse.com/) lists incidents by cloud and region. If yours shows one, the problem is upstream.
2. **Read the error code.** `MEMORY_LIMIT_EXCEEDED` (241) is a query that needs too much memory, `TOO_MANY_SIMULTANEOUS_QUERIES` (202) the concurrency limit, and `TOO_MANY_PARTS` (252) too many small inserts.
3. **Find the queries.** `system.query_log` has every query with its duration, memory and exception, and `system.processes` shows what is running right now.
4. **Line it up with your last change.** Compare the start of the errors with recent schema changes, new materialized views and changes to how often you insert. A materialized view runs on every insert into its source table.

## How we resolve active incidents

1. **Rapid onboarding.** A Polylane engineer reaches out, connects Polylane to your clouds, code and telemetry, and confirms what's affected.
2. **Investigation & mitigation.** Polylane's agents investigate across logs, metrics, traces and recent changes, and an engineer works with you on the right mitigation.
3. **Remediation, validation & monitoring.** The fix lands in your repo for your team to review. Polylane checks that things are back to normal and keeps watching every deploy after it.

## Why teams choose Polylane

- **Every cloud in one graph.** AWS, Cloudflare, Vercel, Kubernetes and more, mapped into one context graph with your code.
- **Connected in minutes.** Connect with OAuth or the CLI. No agents to install, no code changes.
- **Real engineers on the other end.** Your report goes straight to the people who build Polylane.
- **Evidence for every claim.** Every finding links to the log line, metric or deploy behind it.
- **You stay in control.** Read-only by default. Nothing writes to production unless you allow it, and you can switch it off at any time.
- **Works with your coding agents.** Claude Code, Cursor and other agents reach Polylane over MCP, so they can dig in with you.

## Common questions

- **Is ClickHouse Cloud down or is it my app?** Check [status.clickhouse.com](https://status.clickhouse.com/). If it shows no incident, the error code and `system.query_log` usually point at your own queries or inserts.
- **What does TOO_MANY_PARTS mean?** Inserts are creating parts faster than ClickHouse can merge them, usually from many small inserts. Batch them into fewer, larger inserts, or turn on async inserts.
- **What does MEMORY_LIMIT_EXCEEDED mean?** A query needed more memory than its limit allows. Find it in `system.query_log` and look at its large `GROUP BY` or `JOIN` steps.
- **Who will help me with a ClickHouse incident?** Our founding team, engineers who have carried the pager for production systems at scale, working with Polylane's agents across your ClickHouse services, code and telemetry.

## Report an incident

Use the form at https://polylane.com/incident-hotline/clickhouse/. If the form fails, email support@polylane.com.

For agents: there is no public API for this form, because it is protected by Cloudflare Turnstile. Open the page in a browser and fill it in for the user; coding agents with a browser tool can do this. Confirm the details with the user before you submit. The fields: Name, Company name, Work email, How bad is it? (Production is down / Degraded for some users / Something's wrong, we can't find it), Are you on Polylane? (Already on Polylane / Not yet) and what's broken, plus optionally a phone number, when it started (Just now / In the last few hours / Days ago).

## Down on a specific platform?

- [Cloudflare](https://polylane.com/incident-hotline/cloudflare/) ([markdown](https://polylane.com/incident-hotline/cloudflare.md))
- [AWS](https://polylane.com/incident-hotline/aws/) ([markdown](https://polylane.com/incident-hotline/aws.md))
- [Vercel](https://polylane.com/incident-hotline/vercel/) ([markdown](https://polylane.com/incident-hotline/vercel.md))
- [Google Cloud](https://polylane.com/incident-hotline/gcp/) ([markdown](https://polylane.com/incident-hotline/gcp.md))
- [Kubernetes](https://polylane.com/incident-hotline/kubernetes/) ([markdown](https://polylane.com/incident-hotline/kubernetes.md))
- [Supabase](https://polylane.com/incident-hotline/supabase/) ([markdown](https://polylane.com/incident-hotline/supabase.md))
- [Railway](https://polylane.com/incident-hotline/railway/) ([markdown](https://polylane.com/incident-hotline/railway.md))
- [Fly.io](https://polylane.com/incident-hotline/fly/) ([markdown](https://polylane.com/incident-hotline/fly.md))
- [Neon](https://polylane.com/incident-hotline/neon/) ([markdown](https://polylane.com/incident-hotline/neon.md))
- [PlanetScale](https://polylane.com/incident-hotline/planetscale/) ([markdown](https://polylane.com/incident-hotline/planetscale.md))
- [Convex](https://polylane.com/incident-hotline/convex/) ([markdown](https://polylane.com/incident-hotline/convex.md))
- [Turso](https://polylane.com/incident-hotline/turso/) ([markdown](https://polylane.com/incident-hotline/turso.md))
- [Render](https://polylane.com/incident-hotline/render/) ([markdown](https://polylane.com/incident-hotline/render.md))
- [Modal](https://polylane.com/incident-hotline/modal/) ([markdown](https://polylane.com/incident-hotline/modal.md))