Helpful tips

How do you make a Cassandra table?

How do you make a Cassandra table?

Given below is the syntax for creating a table.

  1. Syntax. CREATE (TABLE | COLUMNFAMILY) (” , ”) (WITH AND )
  2. Example.
  3. Verification.
  4. Step1: Create a Cluster Object.
  5. Step 2: Create a Session Object.
  6. Step 3: Execute Query.

How do you find the table structure in Cassandra?


  1. Query the defined keyspaces using the SELECT statement. SELECT * FROM system.schema_keyspaces;
  2. Get the schema information for tables in the cycling keyspace. SELECT * FROM system_schema.
  3. Get details about a table’s columns from system_schema. columns.

What is Cassandra table?

In Cassandra, a table is a list of “nested key-value pairs”. ( ROW x COLUMN key x COLUMN value) Database is the outermost container that contains data corresponding to an application. Keyspace is the outermost container that contains data corresponding to an application. Tables are the entities of a database.

How are Cassandra table sizes calculated?

To calculate the size of a table, we must account for the cluster’s replication factor. Total table size is a function of table data size times the replication factor. Based on the replication factor, Cassandra writes a copy of each partition to other nodes in the cluster.

Can we create table in Cassandra without primary key?

Yes, this does duplicate a lot of data – this is called denormalization, and is common in Cassandra. In future versions (3.4 and higher), you’ll be able to use “SASI”, a new form of Cassandra indexes that may help your use case significantly, with far less denormalization required.

How do you write a query in Cassandra?

What is CQL?

  1. Creating and using key space: cqlsh> CREATE KEYSPACE demodb WITH REPLICATION = { ‘class’ :
  2. Alter Key Space. ALTER KEYSPACE ” demodb ” WITH REPLICATION = { ‘class’ : ‘SimpleStrategy’,
  3. Create Table.
  4. Insert into table.
  5. Select query Select * from emp;

How do I check Cassandra table data?

Cassandra – Read Data

  1. Example. Assume there is a table in the keyspace named emp with the following details −
  2. Step1:Create a Cluster Object. Create an instance of Cluster.
  3. Step 2: Create a Session Object.
  4. Step 3: Execute Query.
  5. Step 4: Get the ResultSet Object.

How do I see all Keyspaces in Cassandra?

Go to data tab > there you will see all keyspcaces created by you and some system keyspaces. You can see all tables under individual keyspaces and also replicator factor for keyspace.

How many partitions can Cassandra have?

The practical limit on the size of a partition is two billion cells, but it is not ideal to have such large partitions. The maximum partition size in Cassandra should be under 100MB and ideally less than 10MB. Application workload and its schema design haves an effect on the optimal partition value.

Is primary key mandatory in Cassandra?

Cassandra is a partition row store, and a component of the primary key, the partition key, identifies which node will hold a particular table row. At the minimum, the primary key must consist of a partition key. Composite partition keys can split a data set so that related data is stored on separate partitions.