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
-- 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
| 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
| 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)