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Coordinator DB
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Inspect query history ​

Use system.query_log to inspect finished work and system.processes to inspect requests that are still running. A query ID connects the request with response metadata and diagnostics.

Enable history ​

sql
SET log_queries = 1;

The setting persists for the selected database. log_queries_min_query_duration_ms can restrict history to requests meeting a duration threshold.

Read terminal events ​

sql
SELECT type, exception_code
FROM system.query_log
WHERE type = 'QueryFinish'
ORDER BY event_time DESC
LIMIT 1
FORMAT csv;
text
"QueryFinish",0

A direct single-table SELECT from system.query_log waits for earlier queued events before reading. The current request's own terminal event appears only after it finishes. A duration threshold can omit short requests and their start events.

Follow a request ​

Use its query_id to select duration, row/byte counters and exception details. Inspect system.processes for an active request rather than expecting its terminal history record before completion.

See query_log, processes and query measurements.