altinity-expert-clickhouse-memory

altinity-expert-clickhouse-memory is a skill for Claude Code, Codex from Altinity/altinity-skills. It costs 37 tokens per session (505 once invoked), scanned A, original, Apache-2.0.

A guide for diagnosing ClickHouse memory use, including high RAM pressure and out-of-memory errors. It examines memory metrics and common causes such as aggregations and joins.

In plain words
What is it for?
Use it to investigate memory-heavy grouping and JOIN operations, check tracked and system memory, and consider limits for joins, threads, and external grouping.
Why use it?
It helps explain why a database process runs out of memory and points to relevant query or configuration areas to inspect.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to investigate memory-heavy grouping and JOIN operations, check tracked and system memory, and consider limits for joins, threads, and external grouping.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/altinity/altinity-skills/altinity-expert-clickhouse-memory
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-memory
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.

agentmods badge for altinity-expert-clickhouse-memory

README.md
[![agentmods](https://agentmods.dev/badge/skills/altinity/altinity-skills/altinity-expert-clickhouse-memory.svg)](https://agentmods.dev/skills/altinity/altinity-skills/altinity-expert-clickhouse-memory)
Your own site
<a href="https://agentmods.dev/skills/altinity/altinity-skills/altinity-expert-clickhouse-memory"><img src="https://agentmods.dev/badge/skills/altinity/altinity-skills/altinity-expert-clickhouse-memory.svg" alt="Measured on agentmods" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 505 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00037 $0.00505
Opus 5 $0.00018 $0.00253
Sonnet 5 $0.00007 $0.00101
Haiku 4.5 $0.00004 $0.00051

Measured 8d ago against content hash 47fd8ea86d34, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

altinity-expert-clickhouse-memory 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 8d 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-memory/SKILL.md · 77 lines

What it actually says

Memory Usage and OOM Diagnostics

Diagnose RAM usage, memory pressure, OOM risks, and memory allocation patterns.


Diagnostics

Run all queries from checks.sql in this skill's directory and analyze the results.


Problem Investigation

High Memory from Aggregations

Solutions:

  • Add max_bytes_before_external_group_by
  • Use max_threads pragma to limit parallelism
  • Restructure query to reduce group by cardinality

High Memory from JOINs

Solutions:

  • Use max_bytes_in_join
  • Consider join_algorithm = 'partial_merge' or 'auto'
  • Ensure smaller table on right side

Ad-Hoc Query Guidelines

Required Safeguards

-- Always time-bound log queries
where event_date >= today() - 1

-- Limit results
limit 100

Memory-Related Metrics

  • MemoryTracking - current tracked memory
  • MemoryResident - RSS
  • OSMemoryTotal, OSMemoryFreeWithoutCached - system memory

Cross-Module Triggers

Finding Load Module Reason
High merge memory altinity-expert-clickhouse-merges Analyze merge patterns
Large dictionaries altinity-expert-clickhouse-dictionaries Dictionary optimization
Cache too large altinity-expert-clickhouse-caches Cache sizing
PK memory high altinity-expert-clickhouse-schema ORDER BY optimization
Query OOMs altinity-expert-clickhouse-reporting Query optimization

Settings Reference

Setting Scope Notes
max_memory_usage Query Per-query limit
max_memory_usage_for_user User Per-user aggregate
max_server_memory_usage Server Global limit
max_server_memory_usage_to_ram_ratio Server Auto-limit as % of RAM
max_bytes_before_external_group_by Query Spill aggregation to disk
max_bytes_in_join Query Spill join to disk
Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

  1. 8d ago First seen · 77 lines · 37 tokens per session scan A 47fd8ea86d34

Subscribe to this mod's changes

altinity-expert-clickhouse-memory is a skill published in the GitHub repository Altinity/altinity-skills (16 stars, last pushed 11d ago), licensed Apache-2.0. It adds 37 tokens to every session and 505 once invoked, about $0.0002 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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