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?"
Like SELECT COUNT(*) FROM system_schema.tables WHERE keyspace_name = 'yourkeyspace' AND table_name = 'yourtable'; ? works at least for Cassandra. The count isn't necessary you can just see if result set has anything. If your doing it to see if you should create the table you can just run the create statement with an IF NOT EXISTS clause and it will be a noop if its already there.
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)
