Using limit in TWCS sorted table doesn't work

[Yuval Feilchenfeld <yu...@securedtouch.com>]

Hey everyone,

I used to run Cassandra 3.10 and when I updated the version to 3.11.6
(checked also on 3.11.9) the latency of my sorted tables spiked.

See this table:

@cqlsh> DESCRIBE sorted_sessions_by_username;
CREATE TABLE securedtouch.sorted_sessions_by_username (
 app_id text,
 username text,
 start_timestamp bigint,
 session_id text,
 PRIMARY KEY ((app_id, username), start_timestamp, session_id)
) WITH CLUSTERING ORDER BY (start_timestamp DESC, session_id 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.TimeWindowCompactionStrategy',
'compaction_window_size': '4', 'compaction_window_unit': 'DAYS',
'max_threshold': '32', 'min_threshold': '2'}
 AND compression = {'chunk_length_in_kb': '4', 'class':
'org.apache.cassandra.io.compress.LZ4Compressor'}
 AND crc_check_chance = 1.0
 AND dclocal_read_repair_chance = 0.0
 AND default_time_to_live = 5184000
 AND gc_grace_seconds = 10800
 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';


When I search in it with LIMIT 1 it scans all of the sstables =/
Any idea why is it happening? I found this ticket (
https://issues.apache.org/jira/browse/CASSANDRA-8180+**+) but it should
have been fixed a long time ago now...

I'm clueless, anyone please help?