Convert dynamic Cassandra column family to static one - cassandra

Question

Let's say I have a column family in Cassandra that was created using cassandra-cli like this:
create column family users with key_validation_class = UTF8Type and comparator = UTF8Type;
In terms of the thrift to CQL3 migration guide from Datastax this is a dynamic column family.
When viewed from CQL3 client using DESCRIBE TABLE users it looks like this:
CREATE TABLE users (
key text,
column1 text,
value blob,
PRIMARY KEY (key, column1)
) WITH COMPACT STORAGE
AND CLUSTERING ORDER BY (column1 ASC);
That is the expected behavior. What I want is to add column metadata so that the column family is viewed as static.
So I tried this using cassandra-cli:
update column family users
with column_metadata = [{column_name: email, validation_class: UTF8Type}];
However the end result in CQL3 is not what I wanted:
CREATE TABLE users (
key text,
column1 text,
value blob,
email text,
PRIMARY KEY (key, column1)
) WITH COMPACT STORAGE
AND CLUSTERING ORDER BY (column1 ASC);
What I expected is the same result as when I create the column family with the metadata from the beginning:
create column family users2
with key_validation_class = UTF8Type
and comparator = UTF8Type
and column_metadata = [{column_name: email, validation_class: UTF8Type}];
In that case the CQL3 view of this is what I want:
CREATE TABLE users2 (
key text PRIMARY KEY,
email text
) WITH COMPACT STORAGE;
Is there some way how I can add column metadata to a column family that was created without any - so that it would be viewed from CQL3 the same way as if the metadata was provided when the column family was created? Without re-creating the column family, of course.

Answer 1

It's not possible to create static column using the old Thrift API. In fact, a static column is just a trick, e.g. a column with clustering value = NULL so there is only 1 instance of it for each partition key.
See those 2 slides for the explanation (sorry text in French):
http://www.slideshare.net/doanduyhai/cassandra-techniques-de-modlisation-avance/218
http://www.slideshare.net/doanduyhai/cassandra-techniques-de-modlisation-avance/219
You should take this opportunity to migrate to CQL. Thrift is deprecated and even disable by default starting with Cassandra 3.x

Answer 2

Ok I see what you mean. Look at the system keyspace, table schema_columnfamilies.
I think the label of the partition keys and clustering columns are stored there.
It maybe possible to change them but I don't know if it's a good idea to hack into those meta tables directly.
If you have n nodes, you'll probably need to update the label on all those nodes since the system keyspace has a LocalStrategy.
Execute this query to see the actual labels:
SELECT key_aliases,key_validator,column_aliases,comparator
FROM system.schema_columnfamilies
WHERE keyspace_name='xxx'
AND columnfamily_name='users';