How to execute a "'describe" CQL query with Astyanax

Question

When you use cqlsh with Cassandra you can make a describe query to get the information of a table for example:

DESCRIBE TABLE emp;

And it will give you something like:

CREATE TABLE emp (
  empid int PRIMARY KEY,
  deptid int,
  description text
) ...
....

So how can I query this using Astyanax support for CQL. I was able to query simple SELECT statements with this:

OperationResult<CqlResult<String, String>> result
            = keyspace.prepareQuery(empColumnFamily)
              .withCql("Select * from emp;")
              .execute();

But this isn't working for DESCRIBE statements.

PD: I am really doing this to get the DATA TYPES of the table, parsing it later and obtaining for example int, int, text, so please if you have a different approach to get those, it could be awesome.

This query select column, validator from system.schema_columns; doesn't work because it doesn't return the composite keys.

Answer 1

DESCRIBE is not part of the CQL spec (neither CQL2 nor CQL3). If you'd like to completely reconstruct the DESCRIBE you could take a look at cqlsh implementation (look for print_recreate_columnfamily).

You could also get some more meta info from system.schema_columnfamilies:

select keyspace_name, columnfamily_name, key_validator from schema_columnfamilies;