Storage and Disk Usage Analysis
Diagnose disk usage, compression efficiency, part sizes, and storage bottlenecks.
Diagnostics
Run all queries from the file checks.sql and analyze the results.
Ad-Hoc Query Guidelines
Required Safeguards
sql
-- 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
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 |
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) |