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ALM-45437 Excessive Parts in the ClickHouse Table

This section applies only to MRS 3.3.0 or later.

Alarm Description

This alarm is generated when the number of parts exceeds the threshold specified by part_num_threshold.

This alarm is automatically cleared when the number of parts is less than the part_num_threshold value.

Alarm Attributes

Alarm ID	Alarm Severity	Auto Cleared
45437	Minor	Yes

Alarm Parameters

Parameter	Description
Source	Specifies the cluster or system for which the alarm is generated.
ServiceName	Specifies the service for which the alarm is generated.
RoleName	Specifies the role for which the alarm is generated.
Table	Specifies the database name and table name for which the alarm is generated.
HostName	Specifies the host for which the alarm is generated.

Impact on the System

Service errors may occur.

Possible Causes

The data distribution in the ClickHouse table is improper, or the background merge task is executed slowly.

Handling Procedure

1. Log in to FusionInsight Manager, choose O&M > Alarm > Alarms, and view the role name and the IP address for the hostname in Location.
2. Log in to the node where the client is installed as the client installation user and run the following commands:

   cd {Client installation path}

   source bigdata_env

   • Security mode (with Kerberos enabled):

     kinit Component service user

     clickhouse client --host IP address of the ClickHouseServer instance that reports the alarm --port 9440 --secure

   • Normal mode (with Kerberos disabled):

     clickhouse client --host IP address of the ClickHouseServer instance that reports the alarm --user Username --password --port 9000

3. Run the following command to manually merge parts:

   optimize table Database name.Table name final;

4. Check whether the number of parts has decreased.

   select FQDN(), database, table, count(1) from clusterAllReplicas(default_cluster, system.parts) where database='Database name' and table='Table name' and active=1 group by (FQDN(), database, table);

   1. If the number of parts is less than the threshold, wait for 5 minutes and check whether the alarm is cleared.
      • If yes, no further action is required.
      • If no, go to 5.
   2. If the number of parts does not decrease, check whether the partition key of the table is set properly. If the number of partitions is too large, rectify the service logic.
   3. If the command output is empty, the table does not exist. This alarm is a historical alarm and can be ignored. Manually clear it.

Collect fault information.

5. On FusionInsight Manager, choose O&M. In the navigation pane on the left, choose Log > Download.
6. Expand the Service drop-down list, and select ClickHouse for the target cluster.
7. Expand the Hosts drop-down list. In the Select Host dialog box that is displayed, select the abnormal host, and click OK.
8. Click the edit icon in the upper right corner, and set Start Date and End Date for log collection to 1 hour ahead of and after the alarm generation time, respectively. Then, click Download.
9. Contact O&M personnel and provide the collected logs.

Alarm Clearance

This alarm is automatically cleared after the fault is rectified.

Related Information

None.

Parent topic: Alarm Reference (Applicable to MRS 3.x)