I have created this table:

```
CREATE TABLE postsbyuser(
  userid bigint,
  posttime timestamp,
  postid uuid,
  postcontent text,
  year bigint,
  PRIMARY KEY ((userid,year), posttime)
) WITH CLUSTERING ORDER BY (posttime DESC); 

```

my Query is to get all user posts in one year ordered by desc posttime.
with the ordering is everything ok, but the problem is that the posttime will be changed if the user edits the postcontent:

```
update postsbyuser set postcontent='edited content' and posttime=edit_time where userid=id and year=year

```

I get the Error : `[Invalid query] message="PRIMARY KEY part time found in SET part"`

have you any idea how to order the posts with a changing time ?