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name: altinity-expert-clickhouse-storage description: Diagnose ClickHouse disk usage, compression efficiency, part sizes, and storage bottlenecks. Use for disk space issues and slow IO.

Storage and Disk Usage Analysis

Diagnose disk usage, compression efficiency, part sizes, and storage bottlenecks.

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Diagnostics

Run all queries from the file checks.sql and analyze the results.

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Ad-Hoc Query Guidelines

Required Safeguards

-- Always limit results
limit 100

-- For part_log
where event_date >= today() - 1

Key Tables

• system.disks - Disk configuration
• system.parts - Part storage details
• system.columns - Column compression
• system.storage_policies - Tiered storage
• system.detached_parts - Orphaned parts

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Cross-Module Triggers

Finding	Load Module	Reason
Poor compression	altinity-expert-clickhouse-schema	Codec recommendations
Many small parts	altinity-expert-clickhouse-merges	Merge backlog
High write IO	altinity-expert-clickhouse-ingestion	Batch sizing
System logs large	altinity-expert-clickhouse-logs	TTL configuration
Slow disk + merges	altinity-expert-clickhouse-merges	Merge optimization

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Settings Reference

Setting	Notes
min_bytes_for_wide_part	Threshold for Wide vs Compact parts
min_rows_for_wide_part	Row threshold for Wide parts
max_bytes_to_merge_at_max_space_in_pool	Max merge size
prefer_not_to_merge	Disable merges (emergency)