ClickHouse/ClickHouse

system.query_log table is not documented

bobrik opened this issue · 7 comments

bobrik commented

What's the meaning of type column? — that was my initial question, though.

alexey-milovidov commented

https://github.com/BayoNet is going to add the documentation.

What's the meaning of type column? — that was my initial question, though.

1 - successful start of query execution
2 - successful end of query execution
3 - exception before start of query execution
4 - exception while query execution

Each query create one or two events in query_log table:

  • two events with types 1 and 2: usual, successful case;
  • two events with types 1 and 4;
  • single event with type 3;
  • 👍6
hagen1778 commented

Are there any way to avoid writing INSERT queries into query_log ?

alexey-milovidov commented

There is no way. Please note, that INSERTs are logged without data.

  • 👍2
jangorecki commented

can I safely truncate query_log table?

filimonov commented

can I safely truncate query_log table?

Yes, it's 100% safe.

filimonov commented

Documentation is added and available on the official website:
https://clickhouse.yandex/docs/en/operations/system_tables/#system_tables-query-log