I need to select distinct count in table in cassandra.
As I understand direct distinct count is not supported in cassandra not even nested queries like rdbms.
select count(*) from (select distinct key_part_one from stackoverflow_composite) as count;
SyntaxException: line 1:21 no viable alternative at input '(' (select count(*) from [(]...)
What are the ways to get it. whether I can get directly from cassandra or any addon tools/languages need to be used?
below is my create table statement.
CREATE TABLE nishant_ana.ais_profile_table (
profile_key text,
profile_id text,
last_update_day date,
last_transaction_timestamp timestamp,
last_update_insertion_timestamp timeuuid,
profile_data blob,
PRIMARY KEY ((profile_key, profile_id), last_update_day)
) WITH CLUSTERING ORDER BY (last_update_day DESC)
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';
I have just started using cassandra.
From Cassandra you can only do the select distinct partition_key from ...
.
If you need something like this, you can use Spark + Spark Cassandra Connector - it will work, but don't expect really real-time answers, as it needs to read necessary data from all nodes, and then calculate answer.