The Workload tab
The Workload tab shows you what’s happening in your ClickHouse® cluster now:
Figure 1 - The Workload tab
It has four subtabs:
- The Running Queries tab - Lists all of the currently running queries.
- The Query Stats tab - Displays statistics for the queries run against this database.
- The Replication Queue tab - Shows any replications in progress.
- The Mutations tab - Lists all mutations currently in progress, with an option to see completed mutations as well.
- The Kafka tab - Lists the tables that interact with Kafka servers and metrics for those tables.
The Running Queries tab
The Running Queries tab shows the details of all the currently running queries:
Figure 2 - The Running Queries tab
Selecting one or more queries activates the 
button. Be aware that not all queries can be killed; if you’d like to know more, see the Altinity Knowledge Base article on killing queries.
The Query Stats tab
The Query Stats tab gives you insight on how your queries are performing:
Figure 3 - The Query Stats tab
Statistics include the average run time for a query, the maximum run time for a query, the average memory used, and how many bytes were read or written for a query. You can see statistics for queries across different time frames (an hour, a day, a week, or a month).
Clicking on an individual query displays a long list of details for that query, such as its status, when it was run, how long it took to execute, and how many bytes and rows were read and written. Here are a few of those details:
Figure 4 - Details of a query
The Replication Queue tab
The Replication Queue tab displays any replications that are in progress:
Figure 5 - The Replication Queue tab
Statistics include the database and table involved for each replication, details about exceptions, postponed replications, and the number of times a replication was tried.
The Mutations tab
The Mutations tab displays information about mutations (ALTER TABLE commands), with the option to display details for any completed mutations:
Figure 6 - The Mutations tab
For each mutation, the display includes information about the host, database, and table being mutated, the command used, and any failures, along with other useful data.
Selecting one or more mutations activates the 
button.
See the ClickHouse documentation for more details on the ALTER TABLE command.
The Kafka tab
The Kafka tab displays information about the tables connected to Kafka servers and metrics about those tables.
Figure 7 - The Kafka tab
When you visit this tab, you must select a node or all nodes to view the data. The Kafka tab has two subtabs: Tables, which lists the tables connected to Kafka servers, and Metrics, which displays metrics for those tables as they ingest data from Kafka.
The Tables subtab looks ike this:
Figure 8 - The Kafka tables subtab
The table shows the databases and tables that are subscribed to a particular Kafka topic. It includes details such as the total number of messages consumed by those tables and how many times they committed data to a ClickHouse table.
The Metrics subtab looks like this:
Figure 9 - The Kafka metrics subtab
The table shows a variety of statistics for the Kafka-connected tables on this node. Only non-zero values are displayed; you can click the Show empty values slider to see every metric if you want.