Question

为什么“SELECT DISTINCT”在CQL3中不起作用？我在这里做错了什么？

请帮我解决此问题。根据CQL3文档，DISTINCT应该使用分区键。

[root@ip-10-12-75-197 /]# cqlsh
Connected to Test Cluster at localhost:9160.
[cqlsh 3.1.7 | Cassandra 1.2.11.2 | CQL spec 3.0.0 | Thrift protocol 19.36.1]
Use HELP for help.

cqlsh> use acks;

cqlsh:acks> describe table actest1;

CREATE TABLE actest1 (
  id int,
  phone int,
  name text,
  PRIMARY KEY (id, phone)
) WITH
  bloom_filter_fp_chance=0.010000 AND
  caching='KEYS_ONLY' AND
  comment='' AND
  dclocal_read_repair_chance=0.000000 AND
  gc_grace_seconds=864000 AND
  read_repair_chance=0.100000 AND
  replicate_on_write='true' AND
  populate_io_cache_on_flush='false' AND
  compaction={'class': 'SizeTieredCompactionStrategy'} AND
  compression={'sstable_compression': 'SnappyCompressor'};

cqlsh:acks> select * from actest1;

 id | phone | name
----+-------+------
  1 |   111 |  ac1
  2 |   111 |  ac2
  3 |   333 |  ac2

cqlsh:acks> select distinct id from actest1;
Bad Request: line 1:16 no viable alternative at input 'id'

cqlsh:acks>

Answer 1

您使用的CQLSH版本使用的是CQL 3.0.0，在3.1.1之前不能使用distinct。

来自手册

3.1.1

SELECT statement now allows listing the partition keys (using the DISTINCT modifier). See CASSANDRA-4536.
The syntax c IN ? is now supported in WHERE clauses. In that case, the value expected for the bind variable will be a list of whatever type c is.
It is now possible to use named bind variables (using :name instead of ?).

http://cassandra.apache.org/doc/cql3/CQL.html

为什么“SELECT DISTINCT”在CQL3中不起作用？

1 个答案: