Friday, March 13, 2026

system.query_log does not existed in the Clickhouse Quick Install

It seems to be the Quick Install does not contain the system.query_log table. The config.xml does not have the entry within and even inserted the query_log section. Restarted the ClickHouse server, the table still does not appear. Did the SYSTEM FLUSH LOGS and that did not trigger the creation of the table as well.


SELECT name, value FROM system.settings WHERE name LIKE 'log_queries'
┌─name────────┬─value─┐
│ log_queries │ 1 │
└──────────┴────┘

Inserted the following according to what has been suggested by the Clickhouse blog, and it did not trigger the query_log table creation.

https://github.com/ClickHouse/ClickHouse/issues/11194


<query_log>
<database>system</database>
<table>query_log</table>
<engine>Engine = MergeTree PARTITION BY event_date ORDER BY event_time TTL event_date + INTERVAL 30 day</engine>
<flush_interval_milliseconds>7500</flush_interval_milliseconds>
<max_size_rows>1048576</max_size_rows>
<reserved_size_rows>8192</reserved_size_rows>
<buffer_size_rows_flush_threshold>524288</buffer_size_rows_flush_threshold>
<flush_on_crash>false</flush_on_crash>
</query_log>


However, the full install do contain the system.query_log table by default.

https://clickhouse.com/docs/install/debian_ubuntu


I think this could be the reason. The Quick Install (https://clickhouse.com/docs/install/quick-install-curl) starts up Clickhouse with ./clickhouse server. While looking at the ps -ef|grep clickhouse, it does not associate to the config.xml file. 


While with the full install, the Clickhouse started with the (sudo service clickhouse-server start) and ps -ef|grep clickhouse apparently has the config.xml associated with. Upon validating the config.xml, it does the have the query_log block. So, in the case of a Quick Install, the startup will have to call (./clickhouse server -C flag) In order to have the query_log created during the start up, the config.xml will need the query_log section.


shimano@shimano-VirtualBox:~$ ps -ef|grep clickhouse
clickho+ 133853 1 0 13:27 ? 00:00:00 clickhouse-watchdog --config=/etc/clickhouse-server/config.xml --pid-file=/run/clickhouse-server/clickhouse-server.pid
clickho+ 133861 133853 48 13:27 ? 01:11:52 /usr/bin/clickhouse-server --config=/etc/clickhouse-server/config.xml --pid-file=/run/clickhouse-server/clickhouse-server.pid
shimano 137068 136336 0 15:56 pts/2 00:00:00 grep --color=auto clickhouse

This isn't necessarily an issue, but perhaps it needs documentation for the Quick Install on how to start up the ./clickhouse server with config.xml.

No comments:

Post a Comment

Issue trying to back up the clickhouse database

While trying to issue a backup database statement and receiving the following error. Code: 627. DB::Exception: Received from localhost:9000....