Storage and Disk Usage Analysis

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

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Diagnostics

Run all queries from checks.sql in this skill's directory 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) |