Skip to main content
    • Knowledge Base/
    How To Create Table To Query Multiple Remote Clusters

    How to create a table that can query multiple remote clusters

    How to create a table that can query multiple remote clusters

    Question​

    How do I create a table that can query other clusters or instances?

    Answer​

    Below is a simple example to test functionality.

    In this example, ClickHouse Cloud is use but the example will work when using self-hosted clusters also. The targets will need to change to the urls/hosts/dns of a target node or load balancer.

    In cluster A:

    Create the database:

    Create the table:

    Insert some sample rows:

    In cluster B:

    Create the database:

    Create the table:

    Insert sample rows:

    In Cluster C:
    *this cluster will be used to gather the data from the other two clusters, however, can also be used as a source.

    Create the database:

    Create the remote tables with remoteSecure() to connect to the other clusters.
    Definition for remote cluster A table:

    Definition for remote cluster B table:

    Create the merge table to be used to gather results:

    Test the results:

    For more info:
    https://clickhouse.com/docs/en/sql-reference/table-functions/remote
    https://clickhouse.com/docs/en/engines/table-engines/special/merge

    · 3 min read