What is altinity-expert-clickhouse-connection?

A setup skill for connecting to ClickHouse, a database designed for analysing large volumes of data. It checks the connection and establishes shared settings such as the cluster and default diagnostic time range.

Use it first when investigating ClickHouse performance, logs, metrics, or cluster-wide data with the related diagnostic skills.

It verifies the database context before other diagnostic queries run, helping avoid analysing the wrong server, cluster, or time period.

altinity-expert-clickhouse-connection — Skill for Claude Code and Code

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add Altinity/altinity-skills --skill altinity-expert-clickhouse-connection

Clone the repo

git clone --depth 1 https://github.com/Altinity/altinity-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/altinity/altinity-skills/altinity-expert-clickhouse-connection/github.svg)](https://agentmods.dev/skills/altinity/altinity-skills/altinity-expert-clickhouse-connection)

Your own site

<a href="https://agentmods.dev/skills/altinity/altinity-skills/altinity-expert-clickhouse-connection"><img src="https://agentmods.dev/badge/skills/altinity/altinity-skills/altinity-expert-clickhouse-connection/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/altinity/altinity-skills/altinity-expert-clickhouse-connection"><img src="https://agentmods.dev/badge/skills/altinity/altinity-skills/altinity-expert-clickhouse-connection.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 618 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00051	$0.00618
Opus 5	$0.00026	$0.00309
Sonnet 5	$0.00010	$0.00124
Haiku 4.5	$0.00005	$0.00062

Measured 9d ago against content hash bb9eb27b7a84, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

altinity-expert-clickhouse-connection scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

altinity-expert-clickhouse/skills/altinity-expert-clickhouse-connection/SKILL.md · 61 lines

How it starts

The opening of the file, as written. The whole thing — 61 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Connection mode

Decide connection mode first and verify connectivity then:

select
    hostName() as hostname,
    version() as version,
    getMacro('cluster') as cluster_name,
    formatReadableTimeDelta(uptime()) as uptime_human,
    getSetting('max_memory_usage') as max_memory_usage,
    (select value from system.asynchronous_metrics where metric = 'OSMemoryTotal') as os_memory_total

MCP mode

Try to use MCP server with clickhouse in the name. If multiple ClickHouse MCP servers are available, ask the user which one to use. When executing queries by the MCP server, push a single SQL statement to the MCP server (no multi-query!)

Exec mode (clickhouse-client)

if MCP is unavailable, try to run clickhouse-client. Don't rely on env vars. On failure, ask how to run it properly.
Prefer running queries from a .sql file with --queries-file and forcing JSON output (-f JSON) when capturing results to files.

Cluster selection for `clusterAllReplicas('{cluster}', ...)`

Verify from the query results above if a cluster_name (cluster macro var) is not empty. If defined - leave macro as-is.
if not, ask the user to choose from: SELECT DISTINCT cluster FROM system.clusters where not is_local and replace '{cluster}' placeholders in the queries in all .sql files.
if the query above returns nothing, consider single-server mode and automatically rewrite clusterAllReplicas('{cluster}', system.<table>) → system.<table> before execution.

Timeframe default for logs/errors

If the user explicitly provides a timeframe in the initial prompt, use it exactly.
Otherwise always default to last 24 hours:

-- Use this pattern for system.*_log tables and system.errors time filters:
-- WHERE event_time >= now() - INTERVAL 24 HOUR

never extend the time window without an explicit user prompt. If needed, ask the user to extend it

Schema-safe rule

If a query fails with UNKNOWN_IDENTIFIER, run DESCRIBE TABLE system.<table> and drop/adjust only the missing columns.
If a query fails with UNKNOWN_TABLE, skip that query and note the table is disabled or unavailable (e.g., system.part_log, system.detached_parts).

Read the full file on GitHub · 61 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

9d ago First seen · 61 lines · 51 tokens per session scan A bb9eb27b7a84

Subscribe to this mod's changes

altinity-expert-clickhouse-connection is a skill published in the GitHub repository Altinity/altinity-skills (16 stars, last pushed today), licensed Apache-2.0. It adds 51 tokens to every session and 618 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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