ClickHouse/docs/en/operations/system-tables/zookeeper.md
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Co-authored-by: Anna Devyatova <annadevyatova@yandex-team.ru>
Co-authored-by: Sergei Shtykov <bayonet@yandex-team.ru>
Co-authored-by: alexey-milovidov <milovidov@yandex-team.ru>
2020-08-06 11:50:29 +03:00

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# system.zookeeper {#system-zookeeper}
The table does not exist if ZooKeeper is not configured. Allows reading data from the ZooKeeper cluster defined in the config.
The query must have a path equality condition in the WHERE clause. This is the path in ZooKeeper for the children that you want to get data for.
The query `SELECT * FROM system.zookeeper WHERE path = '/clickhouse'` outputs data for all children on the `/clickhouse` node.
To output data for all root nodes, write path = /.
If the path specified in path doesnt exist, an exception will be thrown.
Columns:
- `name` (String) — The name of the node.
- `path` (String) — The path to the node.
- `value` (String) — Node value.
- `dataLength` (Int32) — Size of the value.
- `numChildren` (Int32) — Number of descendants.
- `czxid` (Int64) — ID of the transaction that created the node.
- `mzxid` (Int64) — ID of the transaction that last changed the node.
- `pzxid` (Int64) — ID of the transaction that last deleted or added descendants.
- `ctime` (DateTime) — Time of node creation.
- `mtime` (DateTime) — Time of the last modification of the node.
- `version` (Int32) — Node version: the number of times the node was changed.
- `cversion` (Int32) — Number of added or removed descendants.
- `aversion` (Int32) — Number of changes to the ACL.
- `ephemeralOwner` (Int64) — For ephemeral nodes, the ID of the session that owns this node.
Example:
``` sql
SELECT *
FROM system.zookeeper
WHERE path = '/clickhouse/tables/01-08/visits/replicas'
FORMAT Vertical
```
``` text
Row 1:
──────
name: example01-08-1.yandex.ru
value:
czxid: 932998691229
mzxid: 932998691229
ctime: 2015-03-27 16:49:51
mtime: 2015-03-27 16:49:51
version: 0
cversion: 47
aversion: 0
ephemeralOwner: 0
dataLength: 0
numChildren: 7
pzxid: 987021031383
path: /clickhouse/tables/01-08/visits/replicas
Row 2:
──────
name: example01-08-2.yandex.ru
value:
czxid: 933002738135
mzxid: 933002738135
ctime: 2015-03-27 16:57:01
mtime: 2015-03-27 16:57:01
version: 0
cversion: 37
aversion: 0
ephemeralOwner: 0
dataLength: 0
numChildren: 7
pzxid: 987021252247
path: /clickhouse/tables/01-08/visits/replicas
```
[Original article](https://clickhouse.tech/docs/en/operations/system_tables/zookeeper) <!--hide-->