FAQ.md

What is --connection?

--connection allows you to use predefined connections, that is supported by clickhouse-client (1, 2).

Here is an example in XML format:

<clickhouse>
    <connections_credentials>
        <connection>
            <name>prod</name>
            <hostname>prod</hostname>
            <user>default</user>
            <password>secret</password>
            <!-- <secure>false</secure> -->
            <!-- <skip_verify>false</skip_verify> -->
        </connection>
    </connections_credentials>
</clickhouse>

Or in YAML:

---
connections_credentials:
  prod:
    name: prod
    hostname: prod
    user: default
    password: secret

And later, instead of specifying --url (with password in plaintext, which is highly not recommended), you can use chdig --connection prod.

Why I see IO wait reported as zero?

• You should ensure that ClickHouse uses one of taskstat gathering methods:

  • procfs
  • netlink

• And also for linux 5.14 you should enable kernel.task_delayacct sysctl as well.