Partition key only in Cassandra -

in cassandra, understand default, given primary key(id1, id2), id1 partition key , id2 clustering key.

i want know if can define 2 partition keys without clustering key follows:

primary key ((id1, id2));

your understanding correct.
your primary key ((id1, id2)) correct , specifying one partition key consisting of two columns.

in second case, can query data specifying both columns values. eg:

select * mytable id1=1 , id2=3;

and queries like:

select * mytable id1=1;

will fail because id2 is part of primary key.

Today