doc-exports/docs/geminidb/umn/nosql_02_0009.html

Connecting to a GeminiDB Cassandra Instance Over Public Networks

Scenarios

You can use an ECS or local device to connect to a GeminiDB instance over a public network.

This section describes how to use a Linux ECS to connect to a GeminiDB Cassandra instance over a public network.

Prerequisites

• Bind an EIP to the GeminiDB Cassandra instance node and set security group rules.
• Create an ECS running Linux. For details, see "Creating ECSs" in ECS User Guide.
• Obtain the Cassandra client installation package 3.11.3 from the official website.
• If Python is not installed, download and install Python 2.7 and cassandra-driver 3.11.0 or later.

Connecting to a DB Instance Through a Cassandra Client

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 3.11.3 to the ECS. If Wget fails to be downloaded, download it to your local PC and then upload it to the ECS.

   wget https://archive.apache.org/dist/cassandra/3.11.3/apache-cassandra-3.11.3-bin.tar.gz

   tar -zxvf apache-cassandra-3.11.3-bin.tar.gz

3. Obtain the client tool cqlsh.

   cd apache-cassandra-3.11.3/bin

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 EIP of the node to be connected. Obtain the value from the EIP 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 GeminiDB Cassandra instance, you can perform the following operations:

• Run the HELP command to view all supported commands.

• Run HELP <COMMAND> to query the usage of a command. Example: HELP DESC
• Keyspace syntax
  • Create a keyspace. Example:

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

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

  • Run DESC <keyspace_name> to verify the creation results.
  • Run use <keyspace_name> to switch to the keyspace you created.
  • Run DROP KEYSPACE <keyspace_name> to delete the keyspace you created.
• Table syntax
  • Create a table. Example:

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

    test_table is a table name defined by the following three columns: user_id, age, and user_name. user_id indicates a user ID of the INT data type. age indicates user age of the INT data type. user_name indicates a username of the TEXT data type. The primary key is user_id.

  • Run DESC <table_name> to verify the creation results.
  • Insert data into the table. Example:

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

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

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

  • Run SELECT * FROM <table_name> to query table data.
  • Add a column to the table. Example:

    ALTER TABLE test_table ADD gender text;

  • Update data in a table of a keyspace. Example:

    UPDATE test_keyspace.test_table SET prename = 'user_prename1' WHERE user_id = 1;

    UPDATE test_keyspace.test_table SET prename = 'user_prename2' WHERE user_id = 2;

    UPDATE test_keyspace.test_table SET prename = 'user_prename3' WHERE user_id = 3;

  • Delete data from a table in a keyspace. Example:

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

    DELETE age FROM test_keyspace.test_table WHERE user_id=1;

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

    DELETE FROM test_keyspace.test_table WHERE user_id=2;

  • Clear all records in the table. Example:

    TRUNCATE test_keyspace.test_table;

  • Delete the entire table. Example:

    DROP TABLE test_keyspace.test_table;

Parent topic: Connecting to a GeminiDB Cassandra Instance Over Public Networks