System Log Table Health
Analyze system log table health: TTL configuration, disk usage, freshness, and cleanup.
Diagnostics
Run all queries from the file checks.sql and analyze the results.
TTL Recommendations
| Log Table | Recommended TTL | Notes |
|---|---|---|
| query_log | 7-30 days | Balance debugging vs disk |
| query_thread_log | Disable or 3 days | Very verbose |
| part_log | 14-30 days | Important for RCA |
| trace_log | 3-7 days | Large, mostly for debugging |
| text_log | 7-14 days | Important for debugging |
| metric_log | 7-14 days | Useful for trending |
| asynchronous_metric_log | 7-14 days | Low volume |
| crash_log | 90+ days | Rare, keep longer |
Add TTL Example
sql
-- Example: Add 14-day TTL to query_log -- ALTER TABLE system.query_log MODIFY TTL event_date + INTERVAL 14 DAY;
Force TTL Cleanup
sql
-- Force TTL evaluation and cleanup -- OPTIMIZE TABLE system.query_log FINAL; -- Or: ALTER TABLE system.query_log MATERIALIZE TTL;
Cross-Module Triggers
| Finding | Load Module | Reason |
|---|---|---|
| Logs filling disk | altinity-expert-clickhouse-storage | Disk space analysis |
| query_log missing data | altinity-expert-clickhouse-overview | Error summary + routing |
| High log volume | altinity-expert-clickhouse-ingestion | Batch sizing (affects part_log) |
| No query_log entries | altinity-expert-clickhouse-overview | System configuration |
Settings Reference
| Setting | Notes |
|---|---|
log_queries | Enable query_log |
log_queries_min_query_duration_ms | Minimum duration to log |
log_queries_min_type | Minimum query type to log |
query_log_database | Database for query_log |
part_log_database | Database for part_log |
text_log_level | Minimum level for text_log |