cassandra | A Ruby client for the Cassandra distributed database

Each container has its own localhost (127.0.0.1) address - you need to connect to IP address of your machine (if you use bridge), or maybe better to connect by the name (cassandra)

Data in Cassandra is ordered only inside the Cassandra partition, but partitions themselves aren't sorted by value, and organized by hash of partition key. So when you read data, you can read nearby Cassandra partitions, but they may belong to completely different dates.

So if you have data sorted in Spark, you need to explicitly sort data using the .orderBy

During startup, Cassandra tries to retrieve the host ID by querying the local system table with:

DataStax offers the JDBC driver from Magnitude (formerly Simba) to users at no cost so you should be able to use it with DBeaver.

These are the high-level steps for connecting to a Cassandra cluster with DBeaver:

1. Download the Simba JDBC driver from DataStax
2. Import the Simba JDBC driver
3. Create a new connection to your cluster

1. Go to https://downloads.datastax.com/#odbc-jdbc-drivers.
2. Select Simba JDBC Driver for Apache Cassandra.
3. Select JDBC 4.2.
4. Accept the license terms (click the checkbox).
5. Hit the blue Download button.
6. Once the download completes, unzip the downloaded file.

In DBeaver, go to the Driver Manager and import the Simba JDBC driver as follows:

1. Click the New button
2. In the Libraries tab, click the Add File button
3. Locate the directory where you unzipped the download and add the CassandraJDBC42.jar file.
4. Click the Find Class button which should identify the driver class as com.simba.cassandra.jdbc42.Driver.
5. In the Settings tab, set the following:

• Driver Name: Cassandra
• Driver Type: Generic
• Class Name: com.simba.cassandra.jdbc42.Driver
• URL Template: jdbc:cassandra://{host}[:{port}];AuthMech=1 (set authentication mechanism to 0 if your cluster doesn't have authentication enabled)
• Default Port: 9042

1. Click the OK button to save the driver.

At this point, you should see Cassandra as one of the drivers in the list.

In DBeaver, create a new database connection as follows:

1. Select Cassandra from the drivers list.
2. In the Main tab of the JDBC connection settings, set the following:

• Host: node_ip_address (this could be any node in your cluster)
• Port: 9042 (or whatever you've set as rpc_port in cassandra.yaml)
• Username: your_db_username
• Password: your_db_password

1. Click on the Test Connection button to confirm that the driver configuration is working.
2. Click on the Finish button to save the connection settings.

At this point, you should be able to browse the keyspaces and tables in your Cassandra cluster. Cheers!

Ordinarily in a Cassandra cluster, the best practice is to scale horizontally (not vertically). You want more Cassandra nodes to spread the load out to achieve maximum throughput.

The equivalent in Kubernetes is to scale up your deployment. As you increase the node count, the amount of data on each individual Cassandra node will decrease proportionally.

If you really want to resize the PVC, you will only be able to do it dynamically if you have enabled allowVolumeExpansion. You won't lose data as you do this.

Deleting a STS isn't going to work because by design it will be automatically replaced as you already know. You also won't be able to scale down because there isn't enough capacity (disk space) in your cluster if you do. Cheers!

It doesn't work this way in Cassandra. You need to have a full or partial primary key specified in the DELETE command. If you want to delete by non-primary/partition key, then you need first to find rows with that value, extract primary key, and then delete by primary key.

You can find ways to do that in this answer.

Yes you can get incorrect data if reapir is not done. It also depends on with what consistency you are reading or writing. Generally in production systems writes are done with (Local_one/Local_quorum) and read with Local_quorum.

If you are writing with weak consistency level, then repair becomes important as some of the nodes might not have got the mutations and while reading those nodes may get selected.

For example if you write with consistency level ONE on a table TABLE1 with a replication of 3. Now it may happen your write was written to NodeA only and NodeB and NodeC might have missed the mutation. Now if you are reading with Consistency level LOCAL_QUORUM, it may happen that NodeB and 'NodeC' get selected and they do not return the written data.

Repair is an important maintenance task for Cassandra which should be done periodically and continuously to keep data in healthy state.

As Aaron mentioned in comment, you should be fine with value==null till the new value arrives. I think it will be the best practice because appropriate value of column arrive later, so better to update it at that time. Till then it is better to keep it null. If client application cannot put null check then you can put placeholder value as you defined in your example.

Scylla Manager automates the repair process and allows you to configure how and when repair occurs. When you create a cluster a repair task is automatically scheduled. This task is set to occur each week by default, but you can change it to another time, change its parameters or add additional repair tasks if needed.

Source: https://manager.docs.scylladb.com/stable/repair/index.html

[Edi: Pointing to latest docs]