IN restrictions are not supported on indexed columns

[Dikang Gu]

Hello C* developers:

I have one question, does anyone know why we can not support the IN
restrictions on indexed columns? Is it just because no one is working it?
Or are there any other reasons?

Below is an example query:
====

cqlsh:ks1> describe keyspace;

CREATE KEYSPACE ks1 WITH replication = {'class': 'SimpleStrategy',
'replication_factor': '1'}  AND durable_writes = true;

CREATE TABLE ks1.t1 (
    key int,
    col1 int,
    col2 int,
    value int,
    PRIMARY KEY (key, col1, col2)
) WITH CLUSTERING ORDER BY (col1 ASC, col2 ASC)
    AND bloom_filter_fp_chance = 0.01
    AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
    AND comment = ''
    AND compaction = {'class':
'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy',
'max_threshold': '32', 'min_threshold': '4'}
    AND compression = {'chunk_length_in_kb': '64', 'class': '
org.apache.cassandra.io.compress.LZ4Compressor'}
    AND crc_check_chance = 1.0
    AND dclocal_read_repair_chance = 0.1
    AND default_time_to_live = 0
    AND gc_grace_seconds = 864000
    AND max_index_interval = 2048
    AND memtable_flush_period_in_ms = 0
    AND min_index_interval = 128
    AND read_repair_chance = 0.0
    AND speculative_retry = '99PERCENTILE';

cqlsh:ks1> select * from t1 where key = 1 and col2 in (1) allow filtering;

 key | col1 | col2 | value
-----+------+------+-------
   1 |    1 |    1 |     1
   1 |    2 |    1 |     3

(2 rows)
cqlsh:ks1> select * from t1 where key = 1 and col2 in (1, 2) allow
filtering;
*InvalidRequest: Error from server: code=2200 [Invalid query] message="IN
restrictions are not supported on indexed columns"*
cqlsh:ks1>
=====

Thanks


--
Dikang