Can I write a program to see if a table exists in YugaByte's YCQL (Cassandra) api?

Question

Is there a programmatic way to check if a table exists in YugaByte's YCQL (Cassandra) api?

For example, in Postgres one can do something like:

How to check if a table exists in a given schema

SELECT EXISTS (
   SELECT 1
   FROM   information_schema.tables 
   WHERE  table_schema = 'schema_name'
   AND    table_name = 'table_name'
   );

Is there an equivalent in YCQL?"

Answer 1

Yes, you can do the same for YugaByte DB's YCQL. Here's an example that shows how to check for the existence of a keyspace and that of a table via cqlsh.

Setup:

cqlsh> CREATE KEYSPACE IF NOT EXISTS ksp;

cqlsh> CREATE TABLE IF NOT EXISTS ksp.t(k int PRIMARY KEY, v int);

To check if a keyspace exists

cqlsh> select count(*) from system_schema.keyspaces 
       where keyspace_name = 'ksp';


 count
-------
     1

(1 rows)
cqlsh> select count(*) from system_schema.keyspaces 
       where keyspace_name = 'non-existent-ksp';

 count
-------
     0

(1 rows)

To check if a table exists

cqlsh> select count(*) from system_schema.tables 
       where keyspace_name = 'ksp' and table_name = 't';

 count
-------
     1

(1 rows)
cqlsh> select count(*) from system_schema.tables 
        where keyspace_name = 'ksp' and table_name = 'non-existent-t';

 count
-------
     0

(1 rows)