Problems using secondary index with IN keyword

[Petter von Dolwitz (Hem)]

Hi,

I have a table that (in simplified version) looks like this:

CREATE TABLE mytable (
  a varchar,
  b varchar,
  c varchar
  d timstamp,
  e varchar,
  PRIMARY KEY (a, b, c, d)
);

CREATE INDEX mytable_c_idx ON mytable ( c );

After populating I execute:

SELECT * FROM mytable WHERE c='myvalue';

which works fine. However, using:

SELECT * FROM mytable WHERE c IN ('myvalue');

gives me:
Bad Request: PRIMARY KEY part c cannot be restricted (preceding part b is
either not restricted or by a non-EQ relation)

Can anybody explain this? My aim is to query for more than one value in the
c column. Is this supported?

Thanks,
Petter