How to list all cassandra tables

Question

There are many tables in cassandra database, which contain column titled user_id. The values user_id are referred to user stored in table users. As some users are deleted, I would like to delete orphan records in all tables that contain column titled user_id.

Is there a way to list all tables using CassandraSQLContext or any other built-in method or custom procedure in order to avoid explicitly defining the list of tables?

Answer 1

From cqlsh execute describe tables;

Answer 2

There are system tables which can provide information about stored keyspaces, tables, columns.

Try run follows commands in cqlsh console:

1. Get keyspaces info

   SELECT * FROM system.schema_keyspaces ;

2. Get tables info

   SELECT columnfamily_name FROM system.schema_columnfamilies WHERE keyspace_name = 'keyspace name';

3. Get table info

   SELECT column_name, type, validator FROM system.schema_columns WHERE keyspace_name = 'keyspace name' AND columnfamily_name = 'table name';

Since v 5.0.x Docs

1. Get keyspaces info

   SELECT * FROM system_schema.keyspaces;

2. Get tables info

   SELECT * FROM system_schema.tables WHERE keyspace_name = 'keyspace name';

3. Get table info

   SELECT * FROM system_schema.columns WHERE keyspace_name = 'keyspace_name' AND table_name = 'table_name';

Since v 6.0 Docs

1. Get keyspaces info

   SELECT * FROM system_schema.keyspaces

2. Get tables info

   SELECT * FROM system_schema.tables WHERE keyspace_name = 'keyspace name';

3. Get table info

   SELECT * FROM system_schema.columns WHERE keyspace_name = 'keyspace_name' AND table_name = 'table_name';

Answer 3

desc keyspaces;  // list all databases/collections names
use anyKeyspace;  // select any database
desc tables;      // list all tables in collection/ database

Answer 4

You can achieve what you want using datastax core driver and cluster metadata. Here is an example which will list all the tables in your keyspace and columns in each table:

 Cluster cluster= Cluster.builder().addContactPoint(clusterIp).build();
    Metadata metadata =cluster.getMetadata();

   Collection<TableMetadata> tablesMetadata= metadata.getKeyspace("mykeyspacename").getTables();
    for(TableMetadata tm:tablesMetadata){
        System.out.println("Table name:"+tm.getName());
        Collection<ColumnMetadata> columnsMetadata=tm.getColumns();            
        for(ColumnMetadata cm:columnsMetadata){
            String columnName=cm.getName();
            System.out.println("Column name:"+columnName);
        }
    }