Clickhouse: What does the tailing number of system.query_log_N mean?

[achimbab]

ClickHouse is an excellent OLAP database

While I'm looking for the slow queries, I found many query_log_N and query_thread_log_N tables.

SHOW TABLES

...
│ query_log                      │
│ query_log_0                    │
│ query_log_1                    │
│ query_log_2                    │
│ query_log_3                    │
│ query_log_4                    │
│ query_thread_log               │
│ query_thread_log_0             │
│ query_thread_log_1             │
│ query_thread_log_2             │
│ query_thread_log_3             │
│ query_thread_log_4             │
...

I am developing a monitoring system for slow queries and considered to use the query_log table,

but there are other tables with the same postfix of names.

I wonder what the tailing numbers of tables mean.

Thank you.

[den-crane]

It's renamed after each CH upgrade which changes table's schema

[achimbab]

@den-crane
Thank you for your answer.