zookeeper_connection | ClickHouse Docs

Description

This table does not exist if ZooKeeper is not configured. The ‘system.zookeeper_connection’ table shows current connections to ZooKeeper (including auxiliary ZooKeepers). Each row shows information about one connection.

Columns

name (String) — ZooKeeper cluster’s name.
host (String) — The hostname/IP of the ZooKeeper node that ClickHouse connected to.
port (UInt16) — The port of the ZooKeeper node that ClickHouse connected to.
index (Nullable(UInt8)) — The index of the ZooKeeper node that ClickHouse connected to. The index is from ZooKeeper config. If not connected, this column is NULL.
connected_time (DateTime) — When the connection was established.
session_uptime_elapsed_seconds (UInt64) — Seconds elapsed since the connection was established.
is_expired (UInt8) — Is the current connection expired.
keeper_api_version (UInt8) — Keeper API version.
client_id (Int64) — Session id of the connection.
xid (Int64) — XID of the current session.
enabled_feature_flags (Array(Enum16(‘FILTERED_LIST’ = 0, ‘MULTI_READ’ = 1, ‘CHECK_NOT_EXISTS’ = 2, ‘CREATE_IF_NOT_EXISTS’ = 3, ‘REMOVE_RECURSIVE’ = 4, ‘MULTI_WATCHES’ = 5, ‘CHECK_STAT’ = 6, ‘PERSISTENT_WATCHES’ = 7, ‘CREATE_WITH_STATS’ = 8, ‘TRY_REMOVE’ = 9, ‘LIST_WITH_STAT_AND_DATA’ = 10, ‘GET_CHILDREN_RECURSIVE’ = 11, ‘CREATE_TTL’ = 12, ‘CREATE_CONTAINER’ = 13, ‘MAX_REQUEST_SIZE’ = 14))) — Feature flags which are enabled. Only applicable to ClickHouse Keeper.
availability_zone (String) — Availability zone
session_timeout_ms (UInt64) — Session timeout (in milliseconds)
last_zxid_seen (Int64) — Last zxid seen by the current session.

Examples

SELECT
    name,
    host,
    port,
    index,
    connected_time,
    session_uptime_elapsed_seconds,
    is_expired,
    keeper_api_version,
    client_id,
    xid,
    enabled_feature_flags,
    availability_zone
FROM system.zookeeper_connection;

┌─name────┬─host──────┬─port─┬─index─┬──────connected_time─┬─session_uptime_elapsed_seconds─┬─is_expired─┬─keeper_api_version─┬─client_id─┬─xid─┬─enabled_feature_flags────────────────────────────────────────────────────┬─availability_zone─┐
│ default │ 127.0.0.1 │ 2181 │     0 │ 2025-04-10 14:30:00 │                            943 │          0 │                  0 │       420 │  69 │ ['FILTERED_LIST','MULTI_READ','CHECK_NOT_EXISTS','CREATE_IF_NOT_EXISTS'] │ eu-west-1b        │
└─────────┴───────────┴──────┴───────┴─────────────────────┴────────────────────────────────┴────────────┴────────────────────┴───────────┴─────┴──────────────────────────────────────────────────────────────────────────┴───────────────────┘