ClickHouse/docs/en/operations/system-tables/zookeeper_connection.md
mateng915 5237dd0245
New system table zookeeper connection (#45245)
* Feature: Support new system table to show which zookeeper node be connected

Description:
============
Currently we have no place to check which zk node be connected otherwise using
lsof command. It not convenient

Solution:
=========
Implemented a new system table, system.zookeeper_host when CK Server has zk
this table will show the zk node dir which connected by current CK server

Noted: This table can support multi-zookeeper cluster scenario.

* fixed review comments

* added test case

* update test cases

* remove unused code

* fixed review comments and removed unused code

* updated test cases for print host, port and is_expired

* modify the code comments

* fixed CI Failed

* fixed code style check failure

* updated test cases by added Tags

* update test reference

* update test cases

* added system.zookeeper_connection doc

* Update docs/en/operations/system-tables/zookeeper_connection.md

* Update docs/en/operations/system-tables/zookeeper_connection.md

* Update docs/en/operations/system-tables/zookeeper_connection.md

---------

Co-authored-by: Alexander Tokmakov <tavplubix@gmail.com>
2023-05-19 17:06:43 +03:00

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Markdown

---
slug: /en/operations/system-tables/zookeeper_connection
---
#zookeeper_connection
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](../../sql-reference/data-types/string.md)) — ZooKeeper cluster's name.
- `host` ([String](../../sql-reference/data-types/string.md)) — The hostname/IP of the ZooKeeper node that ClickHouse connected to.
- `port` ([String](../../sql-reference/data-types/string.md)) — The port of the ZooKeeper node that ClickHouse connected to.
- `index` ([UInt8](../../sql-reference/data-types/int-uint.md)) — The index of the ZooKeeper node that ClickHouse connected to. The index is from ZooKeeper config.
- `connected_time` ([String](../../sql-reference/data-types/string.md)) — When the connection was established
- `is_expired` ([UInt8](../../sql-reference/data-types/int-uint.md)) — Is the current connection expired.
- `keeper_api_version` ([String](../../sql-reference/data-types/string.md)) — Keeper API version.
- `client_id` ([UInt64](../../sql-reference/data-types/int-uint.md)) — Session id of the connection.
Example:
``` sql
SELECT * FROM system.zookeeper_connection;
```
``` text
┌─name──────────────┬─host─────────┬─port─┬─index─┬──────connected_time─┬─is_expired─┬─keeper_api_version─┬──────────client_id─┐
│ default_zookeeper │ 127.0.0.1 │ 2181 │ 0 │ 2023-05-19 14:30:16 │ 0 │ 0 │ 216349144108826660 │
└───────────────────┴──────────────┴──────┴───────┴─────────────────────┴────────────┴────────────────────┴────────────────────┘
```