Using a Client to Access a ClickHouse Cluster

You can use SQL to access a cluster on an ECS. For details about how to install the client, see Installing the Client.

The VPC and security group of the cluster to be created must be the same as those of the ECS on the public network. Otherwise, the client cannot access the cluster.

Installing the Client

Prepare a Linux ECS. For details, see Preparing an ECS.
Log in to the CloudTable management console, click Help in the navigation pane on the left, and click Download Client and Client Verification File on the right of the page to download the client installation package and client verification file.

Figure 1 Downloading the ClickHouse client

Install the client and connect to the cluster.

Use the SSH login tool to remotely log in to the Linux ECS through the EIP.
For details, see Login Using an SSH Password in the Elastic Cloud Server User Guide.
Go to the root directory of the SSH login tool.
```
cd /
```
Create a folder in the root directory.
```
mkdir Folder name
```
Go to the directory of the created folder.
```
cd /Folder name/
```
Place the client in the directory.
Decompress the client package.
```
tar  -zxf   Client package name
```
Decompress the client verification file to the same directory as the client.
1. Decompress the client verification file.
```
cd <Path for storing the client verification file >
tar xzvf Client_sha256.tar.gz
```
2. Obtain the client verification code.
```
sha256sum ClickHouse_Client_23.3.tar.gz
```
3. Check the verification code in the client verification file and compare it with the client verification code. A match indicates no tampering, while a mismatch suggests tampering.
```
less ClickHouse_Client_23.3.tar.gz.sha256
```
Load the .so file.
```
sh install.sh
```
Go to the bin directory.
```
cd bin/
```
Grant the 700 permission to the directory.
```
chmod 700 clickhouse
```

Connect to the ClickHouse cluster. For details about the port, see Table 1.

Use the following command to connect to a normal cluster.

./clickhouse client --host Private IP address of the cluster   --port Port --user admin --password Password

For details about the security cluster connection command. For details, see Connecting to a Security Cluster.

./clickhouse client --host Private IP address of the cluster --port port --user admin --password Password --secure --config-file /root/config.xml

Private IP address of the cluster: cluster access address on the cluster details page. Replace it with the access address of the cluster you purchased.
Password: the password set when you purchase the cluster. If there are special characters, use backslashes (\) to escape them. If the password is enclosed in single quotation marks ('), the special characters do not need to be escaped.

**Table 1** Custom security rules
Direction	Action	Port/Range	Type	Destination/Source Address	Usage
Outbound	Allow	All	IPv4/IPv6	0.0.0.0/0	Permit in the outbound direction
Inbound	Allow	8123		Security group of the CloudTable ClickHouse cluster	ClickHouse HTTP port number
	Allow	9000			ClickHouse TCP port number
	Allow	8443			ClickHouse HTTPS port number
	Allow	9440			Secure TCP security port of ClickHouse