Query Tracing

Query tracing is a feature that helps you diagnose performance issues with queries by recording each query's execution time in a system table called _query_trace. You can then analyze the data in this table using the full power of QuestDB's SQL statements.

Query tracing is disabled by default. You can enable it using the following configuration property:

query.tracing.enabled=true

You don't need to restart the database server for this property to take effect; just run the following query to reload the configuration:

SELECT reload_config();

This is an example of what the _query_trace table may contain:

_query_trace;

ts	query_text	execution_micros
2025-01-15T08:52:56.600757Z	telemetry_config LIMIT -1	1206
2025-01-15T08:53:03.815732Z	tables()	1523
2025-01-15T08:53:22.971239Z	'sys.query_trace'	5384

As a simple performance debugging example, to get the text of all queries that took more than 100 ms, run:

SELECT 
    query_text 
FROM query_trace() 
WHERE execution_micros > 100_000
ORDER BY execution_micros DESC;

The _query_trace table will drop data older than 24 hours in order to limit how much storage query tracing uses.