基于时间戳查询的Cassandra ReadTimeoutException

Question

我有Cassandra db表记录

create table records (
id text,
cachedtime timestamp,
data list<frozen<RecordType>>,
PRIMARY KEY (id, cachedtime)       
AND CLUSTERING ORDER BY (cachedtime DESC);

RecordType是UDT，cachedtime是群集密钥，每条记录的TTL是60分钟。

我们正在查询ReadTimeoutException，查询下面的选择查询，其一致性级别为LOCAL_QUORUM，复制因子为2。

select * from records where id= "11" and cachedTime < now 

com.datastax.driver.core.exceptions.ReadTimeoutException: Cassandra   
timeout during read query at consistency LOCAL_QUORUM (2 responses were 
required but only 1 replica responded) 

任何人都可以帮助我，为什么我会遇到这个例外。请同时根据timstamp建议查询没有下限会导致性能问题吗？

请告知