altinity/altinity-expert-clickhouse-caches
altinity-expert-clickhouse/skills/altinity-expert-clickhouse-caches/SKILL.md
Analyze ClickHouse cache systems including mark cache, uncompressed cache, and query cache. Use for cache hit ratio issues and cache tuning.
$ install --global
skillsauthnpx skillsauth add altinity/skills altinity-expert-clickhouse-cachesInstall this skill globally with one command. Works with Claude Code, Cursor, and Windsurf.
Security Scan Results
3 of 9 scanners reported clean
Some scanners were skipped, did not run, or reported a non-clean status. Review each row below.
3
Scanners Passed
9
Scanners in report
Clean
TrivyContainer and dependency vulnerability scanner
95%
Clean
SemgrepStatic code analysis for vulnerabilities
95%
Clean
mcp-scan (Snyk)Model Context Protocol security validation
95%
Skipped
Snyk (dep)Open source security scanning
50%
Skipped
Socket.devSupply chain security analysis
50%
Skipped
VirusTotalMulti-engine malware detection
50%
Skipped
CrowdStrikeAdvanced threat intelligence
50%
Skipped
OSV-ScannerOpen Source Vulnerability database check
50%
Skipped
OWASP Dep-Check
50%
Last scanned: Jun 2, 2026, 2:06 AM190.4s1 file scanned
SKILL.md
- name:
- altinity-expert-clickhouse-caches
- description:
- Analyze ClickHouse cache systems including mark cache, uncompressed cache, and query cache. Use for cache hit ratio issues and cache tuning.
- license:
- Apache-2.0
Cache Analysis and Tuning
Analyze ClickHouse cache systems: mark cache, uncompressed cache, query cache, and compiled expression cache.
Diagnostics
Run all queries from checks.sql in this skill's directory and analyze the results.
Cache Sizing Recommendations
| Cache | Typical Size | Notes | |-------|-------------|-------| | Mark Cache | 5-10% of RAM | Higher if random access patterns | | Uncompressed | 0 (disabled) or 5-10% | Enable only for specific workloads | | Query Cache | 1-5GB | For repeated identical queries | | Compiled Expression | 128MB-1GB | Higher for complex expressions |
Problem Investigation
Poor Mark Cache Hit Ratio
Possible causes:
- Cache too small for working set
- Queries scan many different tables
- Many small queries to cold data
Cache Too Large
If mark cache > 15% RAM:
Solutions:
- Reduce
index_granularityfor tables with excessive marks - Drop unused tables
- Reduce
mark_cache_sizesetting
Cross-Module Triggers
| Finding | Load Module | Reason |
|---------|-------------|--------|
| Cache using too much RAM | altinity-expert-clickhouse-memory | Overall memory analysis |
| Poor hit ratio + high disk IO | altinity-expert-clickhouse-storage | Disk bottleneck |
| Many marks per table | altinity-expert-clickhouse-schema | Consider index_granularity tuning |
| Query cache misses | altinity-expert-clickhouse-reporting | Query pattern analysis |
Settings Reference
| Setting | Scope | Notes |
|---------|-------|-------|
| mark_cache_size | Server | Global mark cache limit |
| uncompressed_cache_size | Server | Set to 0 to disable |
| use_uncompressed_cache | Query | Enable per-query |
| query_cache_max_size | Server | Query result cache |
| use_query_cache | Query | Enable per-query |
Related Skills
altinity/altinity-expert-clickhouse-security
tools
VerifiedTrustedCommunity
Read-only ClickHouse security audit expert for live or exported systems. Use when assessing ClickHouse security posture, reviewing users, roles, grants, settings profiles, row policies, table functions, external sources, table engines, executable UDFs, audit logs, named collections, password hash hygiene, SQL SECURITY DEFINER, impersonation, TLS/network exposure, Keeper/interserver security, encryption at rest, backups, the HTTP interface surface, cluster security, or version-specific ClickHouse security behavior. Diagnoses from SQL/system tables, supplied configuration files, query logs, access metadata, and ClickHouse/Altinity documentation.
10SKILL.mdUpdated Jun 4, 2026
altinity/altinity-expert-clickhouse-grants
tools
VerifiedTrustedCommunity
Diagnose and resolve ClickHouse grant and authentication errors, especially after upgrades. Use when queries fail with ACCESS_DENIED/NOT_ENOUGH_PRIVILEGES, AUTHENTICATION_FAILED/WRONG_PASSWORD/REQUIRED_PASSWORD, or ON CLUSTER privilege errors; when system.* or INFORMATION_SCHEMA access is denied; or when grant behavior changes after version upgrades.
10SKILL.mdUpdated May 11, 2026
altinity/altinity-profiler-clickhouse
tools
VerifiedTrustedCommunity
Profile a ClickHouse cluster via MCP and emit a per-cluster "analyst" Skill the user can save in claude.ai. Activate when the user asks to "profile this ClickHouse", "generate an analyst skill", "build a schema guide", "map the data in this cluster", or regenerate an existing cluster-analyst Skill after schema changes. Works against any ClickHouse with read-only SELECT/SHOW/DESCRIBE access via an `execute_query` MCP tool (e.g. the Altinity MCP server). Outputs a 5-file markdown bundle plus a README.
9SKILL.mdUpdated May 11, 2026
altinity/altinity-expert-clickhouse-storage
tools
VerifiedTrustedCommunity
Diagnose ClickHouse disk usage, compression efficiency, part sizes, and storage bottlenecks. Use for disk space issues and slow IO.
9SKILL.mdUpdated May 11, 2026