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* prefer relative links from root * wip * split aggregate function reference * split system tables
71 lines
2.4 KiB
Markdown
71 lines
2.4 KiB
Markdown
# system.zookeeper {#system-zookeeper}
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The table does not exist if ZooKeeper is not configured. Allows reading data from the ZooKeeper cluster defined in the config.
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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.
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The query `SELECT * FROM system.zookeeper WHERE path = '/clickhouse'` outputs data for all children on the `/clickhouse` node.
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To output data for all root nodes, write path = ‘/’.
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If the path specified in ‘path’ doesn’t exist, an exception will be thrown.
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Columns:
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- `name` (String) — The name of the node.
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- `path` (String) — The path to the node.
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- `value` (String) — Node value.
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- `dataLength` (Int32) — Size of the value.
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- `numChildren` (Int32) — Number of descendants.
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- `czxid` (Int64) — ID of the transaction that created the node.
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- `mzxid` (Int64) — ID of the transaction that last changed the node.
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- `pzxid` (Int64) — ID of the transaction that last deleted or added descendants.
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- `ctime` (DateTime) — Time of node creation.
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- `mtime` (DateTime) — Time of the last modification of the node.
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- `version` (Int32) — Node version: the number of times the node was changed.
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- `cversion` (Int32) — Number of added or removed descendants.
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- `aversion` (Int32) — Number of changes to the ACL.
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- `ephemeralOwner` (Int64) — For ephemeral nodes, the ID of the session that owns this node.
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Example:
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``` sql
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SELECT *
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FROM system.zookeeper
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WHERE path = '/clickhouse/tables/01-08/visits/replicas'
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FORMAT Vertical
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```
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``` text
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Row 1:
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──────
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name: example01-08-1.yandex.ru
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value:
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czxid: 932998691229
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mzxid: 932998691229
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ctime: 2015-03-27 16:49:51
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mtime: 2015-03-27 16:49:51
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version: 0
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cversion: 47
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aversion: 0
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ephemeralOwner: 0
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dataLength: 0
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numChildren: 7
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pzxid: 987021031383
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path: /clickhouse/tables/01-08/visits/replicas
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Row 2:
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──────
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name: example01-08-2.yandex.ru
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value:
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czxid: 933002738135
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mzxid: 933002738135
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ctime: 2015-03-27 16:57:01
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mtime: 2015-03-27 16:57:01
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version: 0
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cversion: 37
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aversion: 0
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ephemeralOwner: 0
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dataLength: 0
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numChildren: 7
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pzxid: 987021252247
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path: /clickhouse/tables/01-08/visits/replicas
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```
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