thevar1able/ClickHouse
1
0
Fork 0
mirror of https://github.com/ClickHouse/ClickHouse.git synced 2024-12-04 21:42:39 +00:00
Code Issues Packages Projects Releases Wiki Activity
0b7af1f26c
ClickHouse/docs/en/sql-reference/distributed-ddl.md
Ivan Blinkov 258d2fd499
[docs] split various kinds of CREATE queries into separate articles (#12328) 
* normalize

* split & adjust links

* re-normalize

* adjust ru links

* adjust ja/tr links

* partially apply e0d19d2aea

* reset contribs
2020-07-09 18:10:35 +03:00

1.0 KiB
Raw Blame History

toc_priority toc_title
32 Distributed DDL

Distributed DDL Queries (ON CLUSTER Clause)

By default the CREATE, DROP, ALTER, and RENAME queries affect only the current server where they are executed. In a cluster setup, it is possible to run such queries in a distributed manner with the ON CLUSTER clause.

For example, the following query creates the all_hits Distributed table on each host in cluster:

CREATE TABLE IF NOT EXISTS all_hits ON CLUSTER cluster (p Date, i Int32) ENGINE = Distributed(cluster, default, hits)

In order to run these queries correctly, each host must have the same cluster definition (to simplify syncing configs, you can use substitutions from ZooKeeper). They must also connect to the ZooKeeper servers.

The local version of the query will eventually be executed on each host in the cluster, even if some hosts are currently not available.

!!! warning "Warning" The order for executing queries within a single host is guaranteed.