Configuring and Importing a Sample Project

Context

Obtain the ClickHouse development sample project and import the project to IntelliJ IDEA to learn the sample project.

Prerequisites

Ensure that the difference between the local PC time and the cluster time is less than 5 minutes. If the time difference cannot be determined, contact the system administrator. You can view the time of the cluster in the lower-right corner on the FusionInsight Manager page.

Scenarios

ClickHouse provides sample projects for multiple scenarios to help you quickly learn ClickHouse projects.

Procedure

1. Obtain the sample project folder clickhouse-examples and Maven configurations in the src directory where the sample code is decompressed. For details, see Obtaining Sample Projects from Huawei Mirrors.
2. In the application development environment, import the sample project to the IntelliJ IDEA development environment.
   1. On the IDEA page, choose File > New > Project from Existing Sources.

      

   2. In the displayed Select File or Directory to Import dialog box, select the pom.xml file in the clickhouse-examples folder and click OK.
   3. Confirm subsequent configurations and click Next. If there is no special requirement, use the default values.
   4. Select the recommended JDK version and click Finish.

3. After the project is imported, modify the clickhouse-example.properties file in the conf directory of the sample project based on the actual environment information.

   loadBalancerIPList=
   sslUsed=false
   loadBalancerHttpPort=21425
   loadBalancerHttpsPort=21426
   CLICKHOUSE_SECURITY_ENABLED=true
   user=
   # Passwords stored in plaintext pose security risks. Store them in ciphertext in configuration files or environment variables.
   password=
   clusterName=default_cluster
   databaseName=testdb
   tableName=testtb
   batchRows=10000
   batchNum=10

   Table 1 Configuration description

   Parameter	Default Value	Definition
   loadBalancerIPList	-	Mandatory. Set this parameter to the IP address list of LoadBalance. Log in to FusionInsight Manager, choose Cluster > Services > ClickHouse > Instance, and check the service IP addresses of all ClickHouseBalancer instances. Use commas (,) to separate multiple IP addresses, for example, 10.10.10.100,10.10.10.101.
   sslUsed	false	Whether to enable SSL encryption. You are advised to set this parameter to true for clusters in security mode.
   loadBalancerHttpPort	21425	HTTP port number of LoadBalance. Log in to FusionInsight Manager, choose Cluster > Services > ClickHouse > Instance, click the corresponding ClickHouseBalancer instance, choose Instance Configurations > All Configurations, search for lb_http_port, and obtain the parameter value. The default value is 21425.
   loadBalancerHttpsPort	21426	HTTPS port number of LoadBalance. If sslUsed is set to true, this parameter cannot be empty. Log in to FusionInsight Manager, choose Cluster > Services > ClickHouse > Instance, click the corresponding ClickHouseBalancer instance, choose Instance Configurations > All Configurations, search for lb_https_port, and obtain the parameter value. The default value is 21426.
   CLICKHOUSE_SECURITY_ENABLED	true	Whether to enable the security mode. Set this parameter to false for a cluster in normal mode.
   user	No default value	Developer user created in Table 1.
   password	No default value	Password of the development user. Passwords stored in plaintext pose security risks. Store them in ciphertext in configuration files or environment variables. NOTE: If the user is created on FusionInsight Manager, you need to change the initial password upon the first login.
   clusterName	default_cluster	ClickHouse logical cluster name. Retain the default value.
   databaseName	testdb	Name of the database to be created in the sample code project. You can change the database name based on the site requirements.
   tableName	testtb	Name of the table to be created in the sample code project. You can change the table name based on the site requirements.
   batchRows	10000	Number of data records written in a batch.
   batchNum	10	Total number of batches in which data is written.

   

   Although ClickHouse has the cluster capability, it does not have a unified access entry. The client needs to directly detect all nodes in the cluster. This is not easy to use. ClickHouse uses the LoadBalance-based deployment architecture to automatically distribute user access traffic to multiple backend nodes, expanding service capabilities to external systems and improving fault tolerance. When a client application requests a cluster, Nginx-based ClickHouseBalancer is used to distribute traffic. In this way, data read/write load and high availability of application access are guaranteed.