我正在对一个有500000行的表执行读取和更新查询，有时在处理了大约300000行之后，甚至在没有节点关闭的情况下，也会出现低于错误的情况。
在一致性为1的读取查询期间，cassandra超时（需要1个响应，但只有0个副本响应）
基础设施详细信息：
有5个cassandra节点，5个spark和3个hadoop节点，每个节点有8个内核和28gb内存，cassandra复制因子是3。
cassandra 2.1.8.621 | dse 4.7.1 | spark 1.2.1 | hadoop 2.7.1。
Cassandra配置：

read_request_timeout_in_ms (ms): 10000
range_request_timeout_in_ms (ms): 10000
write_request_timeout_in_ms (ms): 5000
cas_contention_timeout_in_ms (ms): 1000 
truncate_request_timeout_in_ms (ms): 60000
request_timeout_in_ms (ms): 10000.

我也尝试过同样的工作 read_request_timeout_in_ms （ms）到20000，但没用。
我在两张table上做查询。下面是其中一个表的create语句：
创建表：

CREATE TABLE section_ks.testproblem_section (
    problem_uuid text PRIMARY KEY,
    documentation_date timestamp,
    mapped_code_system text,
    mapped_problem_code text,
    mapped_problem_text text,
    mapped_problem_type_code text,
    mapped_problem_type_text text,
    negation_ind text,
    patient_id text,
    practice_uid text,
    problem_category text,
    problem_code text,
    problem_comment text,
    problem_health_status_code text,
    problem_health_status_text text,
    problem_onset_date timestamp,
    problem_resolution_date timestamp,
    problem_status_code text,
    problem_status_text text,
    problem_text text,
    problem_type_code text,
    problem_type_text text,
    target_site_code text,
    target_site_text text
    ) WITH 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'}
    AND compression = {'sstable_compression': 
    'org.apache.cassandra.io.compress.LZ4Compressor'}
    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 = '99.0PERCENTILE';

查询：

1. SELECT encounter_uuid, encounter_start_date FROM section_ks.encounters WHERE patient_id = '1234' AND encounter_start_date >= '" + formatted_documentation_date + "' ALLOW FILTERING; 2) UPDATE section_ks.encounters SET testproblem_uuid_set = testproblem_uuid_set + {'1256'} WHERE encounter_uuid = 'd345';