System Management

The following system functions can be used to manage internal system processors, dictionaries, caches and distributed operations.

ClickHouse reference - https://clickhouse.yandex/docs/en/query_language/system/

v.sys.reload_dicts()

Reload all currently LOADED dictionaries.

v.sys.reload_dict(dictionary)

Reload or load a specific dictionary.

  • Parameters
    • dictionary - the name of the dictionary to reload

v.sys.drop_dns_cache()

Reset ClickHouse's internal DNS cache.

v.sys.drop_mark_cache()

Reset the mark cache (useful for performance testing).

v.sys.flush_logs()

Flush logs to the system tables.

v.sys.reload_config()

Reload the ClickHouse configuration.

v.sys.shutdown()

Shuts down the database instance. Note this will terminate your Vulkn instance.

v.sys.kill()

Force kill the database instance (and your Vulkn session).

v.sys.stop_dist_sends(database, table)

Disable background data distribution for the specified table.

  • Parameters
    • database - the database containing the table to operate on
    • table - the table to operate on

v.sys.flush_dist(database, table)

Flush all data to the cluster nodes synchronously.

  • Parameters
    • database - the database containing the table to operate on
    • table - the table to operate on

v.sys.start_dist_sends(database, table)

Restart background data distribution for the specified table.

  • Parameters
    • database - the database containing the table to operate on
    • table - the table to operate on

v.sys.stop_merges(database, table)

Halt merge operations on the specified table.

  • Parameters
    • database - the database containing the table to operate on
    • table - the table to operate on

v.sys.start_merges(database, table)

Start/restart merge operations on the specified table.

  • Parameters
    • database - the database containing the table to operate on
    • table - the table to operate on