Connecting to a GaussDB(for Cassandra) Instance Over Private Networks

Scenarios

This section uses the Linux operating system as an example to describe how to connect an ECS to a GaussDB(for Cassandra) instance over private networks.

Constraints

• The DB instances must be in the same VPC subnet as the ECS.
• The ECS must be allowed in a security group that has access to the DB instances.
  • If the security group that the target DB instance belongs to is the default security group, you do not need to configure security group rules.
  • If the security group that the target DB instance belongs to is not the default security group, check whether the security group rules allow the ECS to connect to the DB instance. For details, see section Configuring Security Group Rules.

    If the security group rules allow the access from the ECS, the ECS can connect to the DB instance.

    If the security group rule does not allow the access from the ECS, you need to add an inbound rule to the security group.

• The default port of the GaussDB(for Cassandra) instance is 8635.

Prerequisites

• Create an ECS running Linux. For details, see "Creating ECSs" in ECS User Guide.
• Obtain the Cassandra client installation package from the Cassandra official website.
• Before using this tool, install the Python dependency package cassandra-driver 3.11.0 or later.

Using the Cassandra Client Tool to Connect to a DB Instance

1. Log in to the ECS. For details, see the section "Logging In to an ECS" in the Elastic Cloud Server User Guide.
2. Upload the Cassandra client installation package to ECS.
3. Obtain the client tool cqlsh.
4. Connect to the DB instance in the directory where the cqlsh tool is located.

   ./cqlsh <DB_HOST> <DB_PORT> -u <DB_USER>

   Example:

   ./cqlsh 192.168.1.8 8635 -u rwuser

   

   • <DB_HOST> indicates the private IP address of the node to be connected. Obtain the value from the Private IP Address column in the node list on the Basic Information page.
   • <DB_PORT> indicates the port number. The default value is 8635 and cannot be changed.
   • <DB_USER> indicates the database account name. The default value is rwuser.

5. Check the connection result. If the following information is displayed, the connection is successful.

   rwuser@cqlsh>

Follow-up Operations

After logging in to the GaussDB(for Cassandra) instance, you can perform the following operations:

• Run the HELP command to view all supported commands.

• HELP <COMMAND>: This command queries the usage of a command. Example: HELP DESC
• Keyspace syntax
  • Create a keyspace. Example:

    CREATE KEYSPACE IF NOT EXISTS nosql WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '3'};

    Set the keyspace name to nosql, replication to SimpleStrategy, and number of replicas to 3.

  • DESC <keyspace_name>: This command verifies the creation result.
  • use <keyspace_name>: This command switches to the keyspace you created.
  • DROP KEYSPACE <keyspace_name>: This command deletes the keyspace you created.
• Table syntax
  • Create a table. Example:

    CREATE TABLE nosql_table(user_id int, age int, user_name text, PRIMARY KEY(user_id));

    The table name is nosql_table, and the following three columns are defined: user_id, age, and user_name. user_id is of the int type and indicates the user ID. age is of the int type and indicates the age of a user. user_name is of the text type and indicates the user name. The primary key is user_id.

  • DESC <table_name>: This command verifies the creation result.
  • Insert data into the table. Example:

    INSERT INTO nosql_table (user_id, age, user_name) VALUES (1, 10, 'user1');

    INSERT INTO nosql_table (user_id, age, user_name) VALUES (2, 20, 'user2');

    INSERT INTO nosql_table (user_id, age, user_name) VALUES (3, 30, 'user3');

  • SELECT * FROM <table_name>: This command queries table data.
  • Add a column to the table. Example

    ALTER TABLE nosql_table ADD gender text;

  • Insert data to the added column. Example:

    UPDATE nosql.nosql_table SET prename = 'user_prename1' WHERE user_id = 1;

    UPDATE nosql.nosql_table SET prename = 'user_prename2' WHERE user_id = 2;

    UPDATE nosql.nosql_table SET prename = 'user_prename3' WHERE user_id = 3;

  • Delete data in a keyspace. Example:

    Delete the age data of the user whose ID is 1.

    DELETE age FROM nosql.nosql_table WHERE user_id=1;

    Delete the entire record of the user whose ID is 2.

    DELETE FROM nosql.nosql_table WHERE user_id=2;

  • Clear all records in the table. Example:

    TRUNCATE nosql.nosql_table;

  • Delete the entire table. Example:

    DROP TABLE nosql.nosql_table;