我需要在cassandra的表中选择不同的计数。
据我所知,cassandra不支持直接非重复计数,甚至rdbms之类的嵌套查询也不支持。
select count(*) from (select distinct key_part_one from stackoverflow_composite) as count;
SyntaxException:行1:21在输入'('处没有可行的选择(从[[] ...中选择count(*)]
有什么方法得到它。我是否可以直接从cassandra或需要使用任何附加工具/语言?
下面是我的创建表语句。
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';
我刚刚开始使用cassandra。